===================

Bug Fixes
---------

- Revert "Skip candidate not providing valid metadata", as that caused pip to be overeager about downloading from the package index. (`9264 <https://github.com/pypa/pip/issues/9264>`_)

===================

Features
--------

- New resolver: Resolve direct and pinned (``==`` or ``===``) requirements first
to improve resolver performance. (`9185 <https://github.com/pypa/pip/issues/9185>`_)
- Add a mechanism to delay resolving certain packages, and use it for setuptools. (`9249 <https://github.com/pypa/pip/issues/9249>`_)

Bug Fixes
---------

- New resolver: The "Requirement already satisfied" log is not printed only once
for each package during resolution. (`9117 <https://github.com/pypa/pip/issues/9117>`_)
- Fix crash when logic for redacting authentication information from URLs
in ``--help`` is given a list of strings, instead of a single string. (`9191 <https://github.com/pypa/pip/issues/9191>`_)
- New resolver: Correctly implement PEP 592. Do not return yanked versions from
an index, unless the version range can only be satisfied by yanked candidates. (`9203 <https://github.com/pypa/pip/issues/9203>`_)
- New resolver: Make constraints also apply to package variants with extras, so
the resolver correctly avoids backtracking on them. (`9232 <https://github.com/pypa/pip/issues/9232>`_)
- New resolver: Discard a candidate if it fails to provide metadata from source,
or if the provided metadata is inconsistent, instead of quitting outright. (`9246 <https://github.com/pypa/pip/issues/9246>`_)

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

- Update vendoring to 20.8

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

- Update documentation to reflect that pip still uses legacy resolver by default in Python 2 environments. (`9269 <https://github.com/pypa/pip/issues/9269>`_)