Avoid upgrading setuptools when creating the venv for distutils_adopt…

…ion tests. Works around issue with upgrading on PyPy.

setup.cfg

@@ -59,7 +59,7 @@ testing =
 	wheel
 	paver
 	pip>=19.1 # For proper file:// URLs support.
-	jaraco.envs
+	jaraco.envs>=2.2
 	pytest-xdist
 	sphinx
 	jaraco.path>=3.2.0

setuptools/tests/test_distutils_adoption.py

@@ -9,11 +9,13 @@
 import path
 
 
-IS_PYPY = '__pypy__' in sys.builtin_module_names
-
-
 class VirtualEnv(jaraco.envs.VirtualEnv):
     name = '.env'
+    # Some version of PyPy will import distutils on startup, implicitly
+    # importing setuptools, and thus leading to BackendInvalid errors
+    # when upgrading Setuptools. Bypass this behavior by avoiding the
+    # early availability and need to upgrade.
+    create_opts = ['--no-setuptools']
 
     def run(self, cmd, *args, **kwargs):
         cmd = [self.exe(cmd[0])] + cmd[1:]
@@ -61,7 +63,6 @@ def test_distutils_local_with_setuptools(venv):
     assert venv.name in loc.split(os.sep)
 
 
-@pytest.mark.xfail('IS_PYPY', reason='pypy imports distutils on startup')
 def test_distutils_local(venv):
     """
     Even without importing, the setuptools-local copy of distutils is