From 79cd5998aa617f772e6b905177c93cb1f55634ec Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Thu, 28 Jul 2022 12:10:50 +0100
Subject: [PATCH 01/17] Add a --python option

---
 src/pip/_internal/cli/cmdoptions.py  |  8 ++++++++
 src/pip/_internal/cli/main_parser.py | 15 +++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/src/pip/_internal/cli/cmdoptions.py b/src/pip/_internal/cli/cmdoptions.py
index 47ed92779e9..84e0e783869 100644
--- a/src/pip/_internal/cli/cmdoptions.py
+++ b/src/pip/_internal/cli/cmdoptions.py
@@ -189,6 +189,13 @@ class PipOption(Option):
     ),
 )
 
+python: Callable[..., Option] = partial(
+    Option,
+    "--python",
+    dest="python",
+    help="Run pip with the specified Python interpreter.",
+)
+
 verbose: Callable[..., Option] = partial(
     Option,
     "-v",
@@ -1029,6 +1036,7 @@ def check_list_path_option(options: Values) -> None:
         debug_mode,
         isolated_mode,
         require_virtualenv,
+        python,
         verbose,
         version,
         quiet,
diff --git a/src/pip/_internal/cli/main_parser.py b/src/pip/_internal/cli/main_parser.py
index 3666ab04ca6..8a79191c8b2 100644
--- a/src/pip/_internal/cli/main_parser.py
+++ b/src/pip/_internal/cli/main_parser.py
@@ -2,9 +2,11 @@
 """
 
 import os
+import subprocess
 import sys
 from typing import List, Tuple
 
+from pip._internal.build_env import _get_runnable_pip
 from pip._internal.cli import cmdoptions
 from pip._internal.cli.parser import ConfigOptionParser, UpdatingDefaultsHelpFormatter
 from pip._internal.commands import commands_dict, get_similar_commands
@@ -57,6 +59,19 @@ def parse_command(args: List[str]) -> Tuple[str, List[str]]:
     #  args_else: ['install', '--user', 'INITools']
     general_options, args_else = parser.parse_args(args)
 
+    # --python
+    if general_options.python:
+        if "_PIP_RUNNING_IN_SUBPROCESS" not in os.environ:
+            pip_cmd = [
+                general_options.python,
+                _get_runnable_pip(),
+            ]
+            pip_cmd.extend(args)
+            # Block recursing indefinitely
+            os.environ["_PIP_RUNNING_IN_SUBPROCESS"] = "1"
+            proc = subprocess.run(pip_cmd)
+            sys.exit(proc.returncode)
+
     # --version
     if general_options.version:
         sys.stdout.write(parser.version)

From 95cf55bf185b41ce029b5349a8a8f016d6c5e8a5 Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Thu, 28 Jul 2022 14:31:10 +0100
Subject: [PATCH 02/17] Add a news file

---
 news/11320.feature.rst | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 news/11320.feature.rst

diff --git a/news/11320.feature.rst b/news/11320.feature.rst
new file mode 100644
index 00000000000..028f16c2bcf
--- /dev/null
+++ b/news/11320.feature.rst
@@ -0,0 +1 @@
+Add a ``--python`` option to specify the Python environment to be managed by pip.

From 42eae5033e33aace218186f8b76b731771268bbd Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Thu, 28 Jul 2022 15:04:35 +0100
Subject: [PATCH 03/17] More flexible handling of the --python argument

---
 src/pip/_internal/cli/main_parser.py | 72 +++++++++++++++++++++++-----
 1 file changed, 60 insertions(+), 12 deletions(-)

diff --git a/src/pip/_internal/cli/main_parser.py b/src/pip/_internal/cli/main_parser.py
index 8a79191c8b2..967d568e22c 100644
--- a/src/pip/_internal/cli/main_parser.py
+++ b/src/pip/_internal/cli/main_parser.py
@@ -2,15 +2,17 @@
 """
 
 import os
+import shutil
 import subprocess
 import sys
-from typing import List, Tuple
+from typing import List, Optional, Tuple
 
 from pip._internal.build_env import _get_runnable_pip
 from pip._internal.cli import cmdoptions
 from pip._internal.cli.parser import ConfigOptionParser, UpdatingDefaultsHelpFormatter
 from pip._internal.commands import commands_dict, get_similar_commands
 from pip._internal.exceptions import CommandError
+from pip._internal.utils.compat import WINDOWS
 from pip._internal.utils.misc import get_pip_version, get_prog
 
 __all__ = ["create_main_parser", "parse_command"]
@@ -47,6 +49,44 @@ def create_main_parser() -> ConfigOptionParser:
     return parser
 
 
+def identify_python_interpreter(python: str) -> Optional[str]:
+    if python == "python" or python == "py":
+        # Run the active Python.
+        # We have to be very careful here, because:
+        #
+        # 1. On Unix, "python" is probably correct but there is a "py" launcher.
+        # 2. On Windows, "py" is the best option if it's present.
+        # 3. On Windows without "py", "python" might work, but it might also
+        #    be the shim that launches the Windows store to allow you to install
+        #    Python.
+        #
+        # We go with getting py on Windows, and if it's not present or we're
+        # on Unix, get python. We don't worry about the launcher on Unix or
+        # the installer stub on Windows.
+        py = None
+        if WINDOWS:
+            py = shutil.which("py")
+        if py is None:
+            py = shutil.which("python")
+        if py:
+            return py
+
+    # TODO: On Windows, `--python .venv/Scripts/python` won't pass the
+    #       exists() check (no .exe extension supplied). But it's pretty
+    #       obvious what the user intends. Should we allow this?
+    if os.path.exists(python):
+        if not os.path.isdir(python):
+            return python
+        # Might be a virtual environment
+        for exe in ("bin/python", "Scripts/python.exe"):
+            py = os.path.join(python, exe)
+            if os.path.exists(py):
+                return py
+
+    # Could not find the interpreter specified
+    return None
+
+
 def parse_command(args: List[str]) -> Tuple[str, List[str]]:
     parser = create_main_parser()
 
@@ -60,17 +100,25 @@ def parse_command(args: List[str]) -> Tuple[str, List[str]]:
     general_options, args_else = parser.parse_args(args)
 
     # --python
-    if general_options.python:
-        if "_PIP_RUNNING_IN_SUBPROCESS" not in os.environ:
-            pip_cmd = [
-                general_options.python,
-                _get_runnable_pip(),
-            ]
-            pip_cmd.extend(args)
-            # Block recursing indefinitely
-            os.environ["_PIP_RUNNING_IN_SUBPROCESS"] = "1"
-            proc = subprocess.run(pip_cmd)
-            sys.exit(proc.returncode)
+    if general_options.python and "_PIP_RUNNING_IN_SUBPROCESS" not in os.environ:
+        # Re-invoke pip using the specified Python interpreter
+        interpreter = identify_python_interpreter(general_options.python)
+        if interpreter is None:
+            raise CommandError(
+                f"Could not locate Python interpreter {general_options.python}"
+            )
+
+        pip_cmd = [
+            interpreter,
+            _get_runnable_pip(),
+        ]
+        pip_cmd.extend(args)
+
+        # Set a flag so the child doesn't re-invoke itself, causing
+        # an infinite loop.
+        os.environ["_PIP_RUNNING_IN_SUBPROCESS"] = "1"
+        proc = subprocess.run(pip_cmd)
+        sys.exit(proc.returncode)
 
     # --version
     if general_options.version:

From 78e7ea88e98a66a5e0d8dd6574ad3323e13c1a8e Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Fri, 29 Jul 2022 09:37:29 +0100
Subject: [PATCH 04/17] Make get_runnable_pip public

---
 src/pip/_internal/build_env.py       | 4 ++--
 src/pip/_internal/cli/main_parser.py | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/pip/_internal/build_env.py b/src/pip/_internal/build_env.py
index 6d4f6a56eb7..6213eedd14a 100644
--- a/src/pip/_internal/build_env.py
+++ b/src/pip/_internal/build_env.py
@@ -39,7 +39,7 @@ def __init__(self, path: str) -> None:
         self.lib_dirs = get_prefixed_libs(path)
 
 
-def _get_runnable_pip() -> str:
+def get_runnable_pip() -> str:
     """Get a file to pass to a Python executable, to run the currently-running pip.
 
     This is used to run a pip subprocess, for installing requirements into the build
@@ -194,7 +194,7 @@ def install_requirements(
         if not requirements:
             return
         self._install_requirements(
-            _get_runnable_pip(),
+            get_runnable_pip(),
             finder,
             requirements,
             prefix,
diff --git a/src/pip/_internal/cli/main_parser.py b/src/pip/_internal/cli/main_parser.py
index 967d568e22c..61dc42a1298 100644
--- a/src/pip/_internal/cli/main_parser.py
+++ b/src/pip/_internal/cli/main_parser.py
@@ -7,7 +7,7 @@
 import sys
 from typing import List, Optional, Tuple
 
-from pip._internal.build_env import _get_runnable_pip
+from pip._internal.build_env import get_runnable_pip
 from pip._internal.cli import cmdoptions
 from pip._internal.cli.parser import ConfigOptionParser, UpdatingDefaultsHelpFormatter
 from pip._internal.commands import commands_dict, get_similar_commands
@@ -110,7 +110,7 @@ def parse_command(args: List[str]) -> Tuple[str, List[str]]:
 
         pip_cmd = [
             interpreter,
-            _get_runnable_pip(),
+            get_runnable_pip(),
         ]
         pip_cmd.extend(args)
 

From 24c22a3e5d0ad30dcb6fabf68047185496bd21d8 Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Fri, 29 Jul 2022 09:44:14 +0100
Subject: [PATCH 05/17] Check the argument to --python is executable

---
 src/pip/_internal/cli/main_parser.py | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/src/pip/_internal/cli/main_parser.py b/src/pip/_internal/cli/main_parser.py
index 61dc42a1298..6502c567794 100644
--- a/src/pip/_internal/cli/main_parser.py
+++ b/src/pip/_internal/cli/main_parser.py
@@ -71,17 +71,20 @@ def identify_python_interpreter(python: str) -> Optional[str]:
         if py:
             return py
 
-    # TODO: On Windows, `--python .venv/Scripts/python` won't pass the
-    #       exists() check (no .exe extension supplied). But it's pretty
-    #       obvious what the user intends. Should we allow this?
+    # If the named file exists, and is executable, use it.
+    # If it's a directory, assume it's a virtual environment and
+    # look for the environment's Python executable.
     if os.path.exists(python):
-        if not os.path.isdir(python):
+        # Do the directory check first because directories can be executable
+        if os.path.isdir(python):
+            # bin/python for Unix, Scripts/python.exe for Windows
+            # Try both in case of odd cases like cygwin.
+            for exe in ("bin/python", "Scripts/python.exe"):
+                py = os.path.join(python, exe)
+                if os.path.exists(py):
+                    return py
+        elif os.access(python, os.X_OK):
             return python
-        # Might be a virtual environment
-        for exe in ("bin/python", "Scripts/python.exe"):
-            py = os.path.join(python, exe)
-            if os.path.exists(py):
-                return py
 
     # Could not find the interpreter specified
     return None

From 01e122ed4125673c77bfd2aced75e70f6dfa2a7c Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Fri, 29 Jul 2022 10:42:34 +0100
Subject: [PATCH 06/17] Add tests

---
 tests/functional/test_python_option.py | 33 ++++++++++++++++++++++++++
 tests/unit/test_cmdoptions.py          | 31 ++++++++++++++++++++++++
 2 files changed, 64 insertions(+)
 create mode 100644 tests/functional/test_python_option.py

diff --git a/tests/functional/test_python_option.py b/tests/functional/test_python_option.py
new file mode 100644
index 00000000000..4fafde2a8b2
--- /dev/null
+++ b/tests/functional/test_python_option.py
@@ -0,0 +1,33 @@
+import json
+import os
+from pathlib import Path
+from venv import EnvBuilder
+
+from tests.lib import PipTestEnvironment, TestData
+
+
+def test_python_interpreter(
+    script: PipTestEnvironment,
+    tmpdir: Path,
+    shared_data: TestData,
+) -> None:
+    env_path = os.fsdecode(tmpdir / "venv")
+    env = EnvBuilder(with_pip=False)
+    env.create(env_path)
+
+    result = script.pip("--python", env_path, "list", "--format=json")
+    assert json.loads(result.stdout) == []
+    script.pip(
+        "--python",
+        env_path,
+        "install",
+        "-f",
+        shared_data.find_links,
+        "--no-index",
+        "simplewheel==1.0",
+    )
+    result = script.pip("--python", env_path, "list", "--format=json")
+    assert json.loads(result.stdout) == [{"name": "simplewheel", "version": "1.0"}]
+    script.pip("--python", env_path, "uninstall", "simplewheel", "--yes")
+    result = script.pip("--python", env_path, "list", "--format=json")
+    assert json.loads(result.stdout) == []
diff --git a/tests/unit/test_cmdoptions.py b/tests/unit/test_cmdoptions.py
index 1e5ef995cd0..d5b4813822f 100644
--- a/tests/unit/test_cmdoptions.py
+++ b/tests/unit/test_cmdoptions.py
@@ -1,8 +1,12 @@
+import os
+from pathlib import Path
 from typing import Optional, Tuple
+from venv import EnvBuilder
 
 import pytest
 
 from pip._internal.cli.cmdoptions import _convert_python_version
+from pip._internal.cli.main_parser import identify_python_interpreter
 
 
 @pytest.mark.parametrize(
@@ -29,3 +33,30 @@ def test_convert_python_version(
 ) -> None:
     actual = _convert_python_version(value)
     assert actual == expected, f"actual: {actual!r}"
+
+
+def test_identify_python_interpreter_py(monkeypatch: pytest.MonkeyPatch) -> None:
+    def which(cmd: str) -> str:
+        assert cmd == "py" or cmd == "python"
+        return "dummy_value"
+
+    monkeypatch.setattr("shutil.which", which)
+    assert identify_python_interpreter("py") == "dummy_value"
+    assert identify_python_interpreter("python") == "dummy_value"
+
+
+def test_identify_python_interpreter_venv(tmpdir: Path) -> None:
+    env_path = tmpdir / "venv"
+    env = EnvBuilder(with_pip=False)
+    env.create(env_path)
+
+    # Passing a virtual environment returns the Python executable
+    interp = identify_python_interpreter(os.fsdecode(env_path))
+    assert interp is not None
+    assert Path(interp).exists()
+
+    # Passing an executable returns it
+    assert identify_python_interpreter(interp) == interp
+
+    # Passing a non-existent file returns None
+    assert identify_python_interpreter(str(tmpdir / "nonexistent")) is None

From b1eb91204e0673a61d9a3203a49675be3307abd2 Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Fri, 29 Jul 2022 10:57:00 +0100
Subject: [PATCH 07/17] Added documentation

---
 docs/html/user_guide.rst | 43 ++++++++++++++++++++++++++++++++++++++++
 news/11320.feature.rst   |  3 ++-
 2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/docs/html/user_guide.rst b/docs/html/user_guide.rst
index 70a28ab9988..1f1a8660627 100644
--- a/docs/html/user_guide.rst
+++ b/docs/html/user_guide.rst
@@ -782,6 +782,49 @@ This is now covered in :doc:`../topics/repeatable-installs`.
 
 This is now covered in :doc:`../topics/dependency-resolution`.
 
+.. _`Managing a different Python interpreter`:
+
+Managing a different Python interpreter
+=======================================
+
+Occasionally, you may want to use pip to manage a Python installation other than
+the one pip is installed into. In this case, you can use the ``--python`` option
+to specify the interpreter you want to manage. This option can take one of three
+values:
+
+#. The path to a Python executable.
+#. The path to a virtual environment.
+#. Either "py" or "python", referring to the currently active Python interpreter.
+
+In all 3 cases, pip will run exactly as if it had been invoked from that Python
+environment.
+
+One example of where this might be useful is to manage a virtual environment
+that does not have pip installed.
+
+.. tab:: Unix/macOS
+
+   .. code-block:: console
+
+      $ python -m venv .venv --without-pip
+      $ python -m pip --python .venv install SomePackage
+      [...]
+      Successfully installed SomePackage
+
+.. tab:: Windows
+
+   .. code-block:: console
+
+      C:\> py -m venv .venv --without-pip
+      C:\> py -m pip --python .venv install SomePackage
+      [...]
+      Successfully installed SomePackage
+
+You could also use ``--python .venv/bin/python`` (or on Windows,
+``--python .venv\Scripts\python.exe``) if you wanted to be explicit, but the
+virtual environment name is shorter and works exactly the same.
+
+
 .. _`Using pip from your program`:
 
 Using pip from your program
diff --git a/news/11320.feature.rst b/news/11320.feature.rst
index 028f16c2bcf..843eac7c9f4 100644
--- a/news/11320.feature.rst
+++ b/news/11320.feature.rst
@@ -1 +1,2 @@
-Add a ``--python`` option to specify the Python environment to be managed by pip.
+Add a ``--python`` option to allow pip to manage Python environments other
+than the one pip is installed in.

From f86a140b124bef3c4a6beeaa5d6fff1a4cd62a18 Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Fri, 29 Jul 2022 16:59:31 +0100
Subject: [PATCH 08/17] Move docs to a topic

---
 docs/html/topics/index.md         |  1 +
 docs/html/topics/python-option.md | 38 +++++++++++++++++++++++++++
 docs/html/user_guide.rst          | 43 -------------------------------
 3 files changed, 39 insertions(+), 43 deletions(-)
 create mode 100644 docs/html/topics/python-option.md

diff --git a/docs/html/topics/index.md b/docs/html/topics/index.md
index 011205a111d..c5e4d36c95f 100644
--- a/docs/html/topics/index.md
+++ b/docs/html/topics/index.md
@@ -18,4 +18,5 @@ local-project-installs
 repeatable-installs
 secure-installs
 vcs-support
+python-option
 ```
diff --git a/docs/html/topics/python-option.md b/docs/html/topics/python-option.md
new file mode 100644
index 00000000000..242784dfbe8
--- /dev/null
+++ b/docs/html/topics/python-option.md
@@ -0,0 +1,38 @@
+# Managing a different Python interpreter
+
+
+Occasionally, you may want to use pip to manage a Python installation other than
+the one pip is installed into. In this case, you can use the `--python` option
+to specify the interpreter you want to manage. This option can take one of three
+values:
+
+1. The path to a Python executable.
+2. The path to a virtual environment.
+3. Either "py" or "python", referring to the currently active Python interpreter.
+
+In all 3 cases, pip will run exactly as if it had been invoked from that Python
+environment.
+
+One example of where this might be useful is to manage a virtual environment
+that does not have pip installed.
+
+````{tab} Unix/macOS
+```{code-block} console
+$ python -m venv .venv --without-pip
+$ python -m pip --python .venv install SomePackage
+[...]
+Successfully installed SomePackage
+```
+````
+````{tab} Windows
+```{code-block} console
+C:\> py -m venv .venv --without-pip
+C:\> py -m pip --python .venv install SomePackage
+[...]
+Successfully installed SomePackage
+```
+````
+
+You could also use `--python .venv/bin/python` (or on Windows,
+`--python .venv\Scripts\python.exe`) if you wanted to be explicit, but the
+virtual environment name is shorter and works exactly the same.
diff --git a/docs/html/user_guide.rst b/docs/html/user_guide.rst
index 1f1a8660627..70a28ab9988 100644
--- a/docs/html/user_guide.rst
+++ b/docs/html/user_guide.rst
@@ -782,49 +782,6 @@ This is now covered in :doc:`../topics/repeatable-installs`.
 
 This is now covered in :doc:`../topics/dependency-resolution`.
 
-.. _`Managing a different Python interpreter`:
-
-Managing a different Python interpreter
-=======================================
-
-Occasionally, you may want to use pip to manage a Python installation other than
-the one pip is installed into. In this case, you can use the ``--python`` option
-to specify the interpreter you want to manage. This option can take one of three
-values:
-
-#. The path to a Python executable.
-#. The path to a virtual environment.
-#. Either "py" or "python", referring to the currently active Python interpreter.
-
-In all 3 cases, pip will run exactly as if it had been invoked from that Python
-environment.
-
-One example of where this might be useful is to manage a virtual environment
-that does not have pip installed.
-
-.. tab:: Unix/macOS
-
-   .. code-block:: console
-
-      $ python -m venv .venv --without-pip
-      $ python -m pip --python .venv install SomePackage
-      [...]
-      Successfully installed SomePackage
-
-.. tab:: Windows
-
-   .. code-block:: console
-
-      C:\> py -m venv .venv --without-pip
-      C:\> py -m pip --python .venv install SomePackage
-      [...]
-      Successfully installed SomePackage
-
-You could also use ``--python .venv/bin/python`` (or on Windows,
-``--python .venv\Scripts\python.exe``) if you wanted to be explicit, but the
-virtual environment name is shorter and works exactly the same.
-
-
 .. _`Using pip from your program`:
 
 Using pip from your program

From b5afdd604831f985427880537d37eb7a35addaa1 Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Fri, 29 Jul 2022 12:54:13 +0100
Subject: [PATCH 09/17] Fix test to cater for packages leaked into venv

---
 tests/functional/test_python_option.py | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/tests/functional/test_python_option.py b/tests/functional/test_python_option.py
index 4fafde2a8b2..8bf16d7a56b 100644
--- a/tests/functional/test_python_option.py
+++ b/tests/functional/test_python_option.py
@@ -11,12 +11,17 @@ def test_python_interpreter(
     tmpdir: Path,
     shared_data: TestData,
 ) -> None:
-    env_path = os.fsdecode(tmpdir / "venv")
+    env_path = os.fspath(tmpdir / "venv")
     env = EnvBuilder(with_pip=False)
     env.create(env_path)
 
     result = script.pip("--python", env_path, "list", "--format=json")
-    assert json.loads(result.stdout) == []
+    before = json.loads(result.stdout)
+
+    # Ideally we would assert that before==[], but there's a problem in CI
+    # that means this isn't true. See https://github.com/pypa/pip/pull/11326
+    # for details.
+
     script.pip(
         "--python",
         env_path,
@@ -26,8 +31,11 @@ def test_python_interpreter(
         "--no-index",
         "simplewheel==1.0",
     )
+
     result = script.pip("--python", env_path, "list", "--format=json")
-    assert json.loads(result.stdout) == [{"name": "simplewheel", "version": "1.0"}]
+    installed = json.loads(result.stdout)
+    assert {"name": "simplewheel", "version": "1.0"} in installed
+
     script.pip("--python", env_path, "uninstall", "simplewheel", "--yes")
     result = script.pip("--python", env_path, "list", "--format=json")
-    assert json.loads(result.stdout) == []
+    assert json.loads(result.stdout) == before

From 61249ed9ee1811ef2693195e21432ebba738574a Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Sat, 30 Jul 2022 16:55:48 +0100
Subject: [PATCH 10/17] Update docs/html/topics/python-option.md

Co-authored-by: Pradyun Gedam <pradyunsg@gmail.com>
---
 docs/html/topics/python-option.md | 14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/docs/html/topics/python-option.md b/docs/html/topics/python-option.md
index 242784dfbe8..877f78b3041 100644
--- a/docs/html/topics/python-option.md
+++ b/docs/html/topics/python-option.md
@@ -16,22 +16,12 @@ environment.
 One example of where this might be useful is to manage a virtual environment
 that does not have pip installed.
 
-````{tab} Unix/macOS
-```{code-block} console
+```{pip-cli}
 $ python -m venv .venv --without-pip
-$ python -m pip --python .venv install SomePackage
+$ pip --python .venv install SomePackage
 [...]
 Successfully installed SomePackage
 ```
-````
-````{tab} Windows
-```{code-block} console
-C:\> py -m venv .venv --without-pip
-C:\> py -m pip --python .venv install SomePackage
-[...]
-Successfully installed SomePackage
-```
-````
 
 You could also use `--python .venv/bin/python` (or on Windows,
 `--python .venv\Scripts\python.exe`) if you wanted to be explicit, but the

From d0b5a8f75dbac35896a394ab27fff5378ee23baf Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Sat, 30 Jul 2022 16:56:09 +0100
Subject: [PATCH 11/17] Update docs/html/topics/python-option.md

Co-authored-by: Pradyun Gedam <pradyunsg@gmail.com>
---
 docs/html/topics/python-option.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/docs/html/topics/python-option.md b/docs/html/topics/python-option.md
index 877f78b3041..435d8ed6774 100644
--- a/docs/html/topics/python-option.md
+++ b/docs/html/topics/python-option.md
@@ -1,5 +1,7 @@
 # Managing a different Python interpreter
 
+```{versionadded} 22.3
+```
 
 Occasionally, you may want to use pip to manage a Python installation other than
 the one pip is installed into. In this case, you can use the `--python` option

From b6be01aee8be13844fa054a5f8c56fa062cc2c21 Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Sun, 31 Jul 2022 11:50:29 +0100
Subject: [PATCH 12/17] Catch errors from running the subprocess

---
 src/pip/_internal/cli/main_parser.py | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/pip/_internal/cli/main_parser.py b/src/pip/_internal/cli/main_parser.py
index 6502c567794..06a61305d05 100644
--- a/src/pip/_internal/cli/main_parser.py
+++ b/src/pip/_internal/cli/main_parser.py
@@ -120,8 +120,13 @@ def parse_command(args: List[str]) -> Tuple[str, List[str]]:
         # Set a flag so the child doesn't re-invoke itself, causing
         # an infinite loop.
         os.environ["_PIP_RUNNING_IN_SUBPROCESS"] = "1"
-        proc = subprocess.run(pip_cmd)
-        sys.exit(proc.returncode)
+        returncode = 0
+        try:
+            proc = subprocess.run(pip_cmd)
+            returncode = proc.returncode
+        except (subprocess.SubprocessError, OSError) as exc:
+            raise CommandError(f"Failed to run pip under {interpreter}: {exc}")
+        sys.exit(returncode)
 
     # --version
     if general_options.version:

From 333389133a9fc5f07280a1025a466b137386b18a Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Sun, 31 Jul 2022 12:12:49 +0100
Subject: [PATCH 13/17] Check python version in __pip-runner__.py

---
 setup.py                  |  2 ++
 src/pip/__pip-runner__.py | 16 ++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/setup.py b/setup.py
index 9b7fdeb1134..2179d34d2bf 100644
--- a/setup.py
+++ b/setup.py
@@ -81,5 +81,7 @@ def get_version(rel_path: str) -> str:
         ],
     },
     zip_safe=False,
+    # NOTE: python_requires is duplicated in __pip-runner__.py.
+    # When changing this value, please change the other copy as well.
     python_requires=">=3.7",
 )
diff --git a/src/pip/__pip-runner__.py b/src/pip/__pip-runner__.py
index 280e99f2f08..28e4399b054 100644
--- a/src/pip/__pip-runner__.py
+++ b/src/pip/__pip-runner__.py
@@ -12,6 +12,8 @@
 from typing import Optional, Sequence, Union
 
 PIP_SOURCES_ROOT = dirname(dirname(__file__))
+# Copied from setup.py
+PYTHON_REQUIRES = ">=3.7"
 
 
 class PipImportRedirectingFinder:
@@ -30,8 +32,22 @@ def find_spec(
         return spec
 
 
+def check_python_version() -> None:
+    # Import here to ensure the imports happen after the sys.meta_path change.
+    from pip._vendor.packaging.specifiers import SpecifierSet
+    from pip._vendor.packaging.version import Version
+
+    py_ver = Version("{0.major}.{0.minor}.{0.micro}".format(sys.version_info))
+    if py_ver not in SpecifierSet(PYTHON_REQUIRES):
+        raise SystemExit(
+            f"This version of pip does not support python {py_ver} "
+            f"(requires {PYTHON_REQUIRES})"
+        )
+
+
 # TODO https://github.com/pypa/pip/issues/11294
 sys.meta_path.insert(0, PipImportRedirectingFinder())
 
 assert __name__ == "__main__", "Cannot run __pip-runner__.py as a non-main module"
+check_python_version()
 runpy.run_module("pip", run_name="__main__", alter_sys=True)

From 4dc35b7399cee3668caf31ba200d3dcfc2bd7579 Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Sun, 31 Jul 2022 16:01:57 +0100
Subject: [PATCH 14/17] Skip the executable check, as subprocess.run will catch
 this

---
 src/pip/_internal/cli/main_parser.py | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/pip/_internal/cli/main_parser.py b/src/pip/_internal/cli/main_parser.py
index 06a61305d05..548174d8dfe 100644
--- a/src/pip/_internal/cli/main_parser.py
+++ b/src/pip/_internal/cli/main_parser.py
@@ -71,11 +71,10 @@ def identify_python_interpreter(python: str) -> Optional[str]:
         if py:
             return py
 
-    # If the named file exists, and is executable, use it.
+    # If the named file exists, use it.
     # If it's a directory, assume it's a virtual environment and
     # look for the environment's Python executable.
     if os.path.exists(python):
-        # Do the directory check first because directories can be executable
         if os.path.isdir(python):
             # bin/python for Unix, Scripts/python.exe for Windows
             # Try both in case of odd cases like cygwin.
@@ -83,7 +82,7 @@ def identify_python_interpreter(python: str) -> Optional[str]:
                 py = os.path.join(python, exe)
                 if os.path.exists(py):
                     return py
-        elif os.access(python, os.X_OK):
+        else:
             return python
 
     # Could not find the interpreter specified

From ebe491a82a13e6610697b22be00db363fb5ff5e3 Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Mon, 1 Aug 2022 10:49:32 +0100
Subject: [PATCH 15/17] Get rid of the --python python/py shortcuts

---
 src/pip/_internal/cli/main_parser.py | 23 -----------------------
 tests/unit/test_cmdoptions.py        | 12 +-----------
 2 files changed, 1 insertion(+), 34 deletions(-)

diff --git a/src/pip/_internal/cli/main_parser.py b/src/pip/_internal/cli/main_parser.py
index 548174d8dfe..5ade356b9c2 100644
--- a/src/pip/_internal/cli/main_parser.py
+++ b/src/pip/_internal/cli/main_parser.py
@@ -2,7 +2,6 @@
 """
 
 import os
-import shutil
 import subprocess
 import sys
 from typing import List, Optional, Tuple
@@ -12,7 +11,6 @@
 from pip._internal.cli.parser import ConfigOptionParser, UpdatingDefaultsHelpFormatter
 from pip._internal.commands import commands_dict, get_similar_commands
 from pip._internal.exceptions import CommandError
-from pip._internal.utils.compat import WINDOWS
 from pip._internal.utils.misc import get_pip_version, get_prog
 
 __all__ = ["create_main_parser", "parse_command"]
@@ -50,27 +48,6 @@ def create_main_parser() -> ConfigOptionParser:
 
 
 def identify_python_interpreter(python: str) -> Optional[str]:
-    if python == "python" or python == "py":
-        # Run the active Python.
-        # We have to be very careful here, because:
-        #
-        # 1. On Unix, "python" is probably correct but there is a "py" launcher.
-        # 2. On Windows, "py" is the best option if it's present.
-        # 3. On Windows without "py", "python" might work, but it might also
-        #    be the shim that launches the Windows store to allow you to install
-        #    Python.
-        #
-        # We go with getting py on Windows, and if it's not present or we're
-        # on Unix, get python. We don't worry about the launcher on Unix or
-        # the installer stub on Windows.
-        py = None
-        if WINDOWS:
-            py = shutil.which("py")
-        if py is None:
-            py = shutil.which("python")
-        if py:
-            return py
-
     # If the named file exists, use it.
     # If it's a directory, assume it's a virtual environment and
     # look for the environment's Python executable.
diff --git a/tests/unit/test_cmdoptions.py b/tests/unit/test_cmdoptions.py
index d5b4813822f..8c33ca8c18d 100644
--- a/tests/unit/test_cmdoptions.py
+++ b/tests/unit/test_cmdoptions.py
@@ -35,23 +35,13 @@ def test_convert_python_version(
     assert actual == expected, f"actual: {actual!r}"
 
 
-def test_identify_python_interpreter_py(monkeypatch: pytest.MonkeyPatch) -> None:
-    def which(cmd: str) -> str:
-        assert cmd == "py" or cmd == "python"
-        return "dummy_value"
-
-    monkeypatch.setattr("shutil.which", which)
-    assert identify_python_interpreter("py") == "dummy_value"
-    assert identify_python_interpreter("python") == "dummy_value"
-
-
 def test_identify_python_interpreter_venv(tmpdir: Path) -> None:
     env_path = tmpdir / "venv"
     env = EnvBuilder(with_pip=False)
     env.create(env_path)
 
     # Passing a virtual environment returns the Python executable
-    interp = identify_python_interpreter(os.fsdecode(env_path))
+    interp = identify_python_interpreter(os.fspath(env_path))
     assert interp is not None
     assert Path(interp).exists()
 

From b8aa21b5759c55bf53f69c185b6193a19e82cd20 Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Wed, 3 Aug 2022 10:05:25 +0100
Subject: [PATCH 16/17] Revert __pip-runner__.py changes

---
 setup.py                  |  2 --
 src/pip/__pip-runner__.py | 16 ----------------
 2 files changed, 18 deletions(-)

diff --git a/setup.py b/setup.py
index 2179d34d2bf..9b7fdeb1134 100644
--- a/setup.py
+++ b/setup.py
@@ -81,7 +81,5 @@ def get_version(rel_path: str) -> str:
         ],
     },
     zip_safe=False,
-    # NOTE: python_requires is duplicated in __pip-runner__.py.
-    # When changing this value, please change the other copy as well.
     python_requires=">=3.7",
 )
diff --git a/src/pip/__pip-runner__.py b/src/pip/__pip-runner__.py
index 41d7fe00474..14026c0d131 100644
--- a/src/pip/__pip-runner__.py
+++ b/src/pip/__pip-runner__.py
@@ -12,8 +12,6 @@
 from typing import Optional, Sequence, Union
 
 PIP_SOURCES_ROOT = dirname(dirname(__file__))
-# Copied from setup.py
-PYTHON_REQUIRES = ">=3.7"
 
 
 class PipImportRedirectingFinder:
@@ -32,21 +30,7 @@ def find_spec(
         return spec
 
 
-def check_python_version() -> None:
-    # Import here to ensure the imports happen after the sys.meta_path change.
-    from pip._vendor.packaging.specifiers import SpecifierSet
-    from pip._vendor.packaging.version import Version
-
-    py_ver = Version("{0.major}.{0.minor}.{0.micro}".format(sys.version_info))
-    if py_ver not in SpecifierSet(PYTHON_REQUIRES):
-        raise SystemExit(
-            f"This version of pip does not support python {py_ver} "
-            f"(requires {PYTHON_REQUIRES})"
-        )
-
-
 sys.meta_path.insert(0, PipImportRedirectingFinder())
 
 assert __name__ == "__main__", "Cannot run __pip-runner__.py as a non-main module"
-check_python_version()
 runpy.run_module("pip", run_name="__main__", alter_sys=True)

From 9b638ec6dcf3b28c8c57b0e08056ee19177f52fd Mon Sep 17 00:00:00 2001
From: Paul Moore <p.f.moore@gmail.com>
Date: Wed, 3 Aug 2022 20:25:40 +0100
Subject: [PATCH 17/17] Update docs to match behaviour

---
 docs/html/topics/python-option.md | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/docs/html/topics/python-option.md b/docs/html/topics/python-option.md
index 435d8ed6774..5ad46e7af9c 100644
--- a/docs/html/topics/python-option.md
+++ b/docs/html/topics/python-option.md
@@ -5,14 +5,13 @@
 
 Occasionally, you may want to use pip to manage a Python installation other than
 the one pip is installed into. In this case, you can use the `--python` option
-to specify the interpreter you want to manage. This option can take one of three
+to specify the interpreter you want to manage. This option can take one of two
 values:
 
 1. The path to a Python executable.
 2. The path to a virtual environment.
-3. Either "py" or "python", referring to the currently active Python interpreter.
 
-In all 3 cases, pip will run exactly as if it had been invoked from that Python
+In both cases, pip will run exactly as if it had been invoked from that Python
 environment.
 
 One example of where this might be useful is to manage a virtual environment