Merge #215

215: Update pip to 21.0.1 r=duckinator a=pyup-bot


This PR updates [pip](https://pypi.org/project/pip) from **20.3.3** to **21.0.1**.



<details>
  <summary>Changelog</summary>
  
  
   ### 21.0.1
   ```
   ===================

Bug Fixes
---------

- commands: debug: Use packaging.version.parse to compare between versions. (`9461 &lt;https://github.com/pypa/pip/issues/9461&gt;`_)
- New resolver: Download and prepare a distribution only at the last possible
  moment to avoid unnecessary network access when the same version is already
  installed locally. (`9516 &lt;https://github.com/pypa/pip/issues/9516&gt;`_)

Vendored Libraries
------------------

- Upgrade packaging to 20.9
   ```
   
  
  
   ### 21.0
   ```
   =================

Deprecations and Removals
-------------------------

- Drop support for Python 2. (`6148 &lt;https://github.com/pypa/pip/issues/6148&gt;`_)
- Remove support for legacy wheel cache entries that were created with pip
  versions older than 20.0. (`7502 &lt;https://github.com/pypa/pip/issues/7502&gt;`_)
- Remove support for VCS pseudo URLs editable requirements. It was emitting
  deprecation warning since version 20.0. (`7554 &lt;https://github.com/pypa/pip/issues/7554&gt;`_)
- Modernise the codebase after Python 2. (`8802 &lt;https://github.com/pypa/pip/issues/8802&gt;`_)
- Drop support for Python 3.5. (`9189 &lt;https://github.com/pypa/pip/issues/9189&gt;`_)
- Remove the VCS export feature that was used only with editable VCS
  requirements and had correctness issues. (`9338 &lt;https://github.com/pypa/pip/issues/9338&gt;`_)

Features
--------

- Add ``--ignore-requires-python`` support to pip download. (`1884 &lt;https://github.com/pypa/pip/issues/1884&gt;`_)
- New resolver: Error message shown when a wheel contains inconsistent metadata
  is made more helpful by including both values from the file name and internal
  metadata. (`9186 &lt;https://github.com/pypa/pip/issues/9186&gt;`_)

Bug Fixes
---------

- Fix a regression that made ``pip wheel`` do a VCS export instead of a VCS clone
  for editable requirements. This broke VCS requirements that need the VCS
  information to build correctly. (`9273 &lt;https://github.com/pypa/pip/issues/9273&gt;`_)
- Fix ``pip download`` of editable VCS requirements that need VCS information
  to build correctly. (`9337 &lt;https://github.com/pypa/pip/issues/9337&gt;`_)

Vendored Libraries
------------------

- Upgrade msgpack to 1.0.2.
- Upgrade requests to 2.25.1.

Improved Documentation
----------------------

- Render the unreleased pip version change notes on the news page in docs. (`9172 &lt;https://github.com/pypa/pip/issues/9172&gt;`_)
- Fix broken email link in docs feedback banners. (`9343 &lt;https://github.com/pypa/pip/issues/9343&gt;`_)


.. note

    You should *NOT* be adding new change log entries to this file, this
    file is managed by towncrier. You *may* edit previous change logs to
    fix problems like typo corrections or such.

    To add a new change log entry, please see
        https://pip.pypa.io/en/latest/development/contributing/#news-entries

.. towncrier release notes start
   ```
   
  
  
   ### 20.3.4
   ```
   ===================

Features
--------

- ``pip wheel`` now verifies the built wheel contains valid metadata, and can be
  installed by a subsequent ``pip install``. This can be disabled with
  ``--no-verify``. (`9206 &lt;https://github.com/pypa/pip/issues/9206&gt;`_)
- Improve presentation of XMLRPC errors in pip search. (`9315 &lt;https://github.com/pypa/pip/issues/9315&gt;`_)

Bug Fixes
---------

- Fixed hanging VCS subprocess calls when the VCS outputs a large amount of data
  on stderr. Restored logging of VCS errors that was inadvertently removed in pip
  20.2. (`8876 &lt;https://github.com/pypa/pip/issues/8876&gt;`_)
- Fix error when an existing incompatibility is unable to be applied to a backtracked state. (`9180 &lt;https://github.com/pypa/pip/issues/9180&gt;`_)
- New resolver: Discard a faulty distribution, instead of quitting outright.
  This implementation is taken from 20.2.2, with a fix that always makes the
  resolver iterate through candidates from indexes lazily, to avoid downloading
  candidates we do not need. (`9203 &lt;https://github.com/pypa/pip/issues/9203&gt;`_)
- New resolver: Discard a source distribution if it fails to generate metadata,
  instead of quitting outright. This implementation is taken from 20.2.2, with a
  fix that always makes the resolver iterate through candidates from indexes
  lazily, to avoid downloading candidates we do not need. (`9246 &lt;https://github.com/pypa/pip/issues/9246&gt;`_)

Vendored Libraries
------------------

- Upgrade resolvelib to 0.5.4.
   ```
   
  
</details>


 

<details>
  <summary>Links</summary>
  
  - PyPI: https://pypi.org/project/pip
  - Changelog: https://pyup.io/changelogs/pip/
  - Homepage: https://pip.pypa.io/
</details>



Co-authored-by: pyup-bot <[email protected]>

setup.cfg

@@ -25,7 +25,7 @@ python_requires = >=3.5
 # FIXME: This name seems wrong, but I can't think of a better one atm.
 build =
     bork==5.1.0
-    pip==20.3.3
+    pip==21.0.1
     setuptools==51.1.1
     wheel==0.36.2