Log Message:
py-setuptools: update to 50.0.1.

Please note the change in 50.0.0:

"Setuptools overrides the stdlib distutils on import"

and the workaround:

"If the environment variable ``SETUPTOOLS_USE_DISTUTILS`` is set to
``stdlib``, Setuptools will fall back to the legacy behavior."

v50.0.1
-------

* #2357: Restored Python 3.5 support in distutils.util for missing \ 
`subprocess._optim_args_from_interpreter_flags`.
* #2358: Restored AIX support on Python 3.8 and earlier.
* #2361: Add Python 3.10 support to _distutils_hack. Get the 'Loader' abstract class
  from importlib.abc rather than importlib.util.abc (alias removed in Python
  3.10).

v50.0.0
-------

* #2232: Once again, Setuptools overrides the stdlib distutils on import. For \ 
environments or invocations where this behavior is undesirable, users are \ 
provided with a temporary escape hatch. If the environment variable \ 
``SETUPTOOLS_USE_DISTUTILS`` is set to ``stdlib``, Setuptools will fall back to \ 
the legacy behavior. Use of this escape hatch is discouraged, but it is provided \ 
to ease the transition while proper fixes for edge cases can be addressed.
* #2334: In MSVC module, refine text in error message.

v49.6.0
-------

* #2129: In pkg_resources, no longer detect any pathname ending in .egg as a \ 
Python egg. Now the path must be an unpacked egg or a zip file.

v49.5.0
-------

* #2306: When running as a PEP 517 backend, setuptools does not try to install
  ``setup_requires`` itself. They are reported as build requirements for the
  frontend to install.

v49.4.0
-------

* #2310: Updated vendored packaging version to 20.4.

v49.3.2
-------

* #2300: Improve the ``safe_version`` function documentation
* #2297: Once again, in stubs prefer exec_module to the deprecated load_module.

v49.3.1
-------

* #2316: Removed warning when ``distutils`` is imported before ``setuptools`` \ 
when ``distutils`` replacement is not enabled.

v49.3.0
-------

* #2259: Setuptools now provides a .pth file (except for editable installs of \ 
setuptools) to the target environment to ensure that when enabled, the \ 
setuptools-provided distutils is preferred before setuptools has been imported \ 
(and even if setuptools is never imported). Honors the SETUPTOOLS_USE_DISTUTILS \ 
environment variable.

v49.2.1
-------

* #2257: Fixed two flaws in distutils._msvccompiler.MSVCCompiler.spawn.

v49.2.0
-------

* #2230: Now warn the user when setuptools is imported after distutils modules \ 
have been loaded (exempting PyPy for 3.6), directing the users of packages to \ 
import setuptools first.

v49.1.3
-------

* #2212: (Distutils) Allow spawn to accept environment. Avoid monkey-patching \ 
global state.
* #2249: Fix extension loading technique in stubs.

v49.1.2
-------

* #2232: In preparation for re-enabling a local copy of distutils, Setuptools \ 
now honors an environment variable, SETUPTOOLS_USE_DISTUTILS. If set to 'stdlib' \ 
(current default), distutils will be used from the standard library. If set to \ 
'local' (default in a imminent backward-incompatible release), the local copy of \ 
distutils will be used.

v49.1.1
-------

* #2094: Removed pkg_resources.py2_warn module, which is no longer reachable.

v49.0.1
-------

* #2228: Applied fix for pypa/distutils#3, restoring expectation that spawn will \ 
raise a DistutilsExecError when attempting to execute a missing file.

v49.1.0
-------

* #2228: Disabled distutils adoption for now while emergent issues are addressed.

v49.0.0
-------

* #2165: Setuptools no longer installs a site.py file during easy_install or \ 
develop installs. As a result, .eggs on PYTHONPATH will no longer take \ 
precedence over other packages on sys.path. If this issue affects your \ 
production environment, please reach out to the maintainers at #2165.
* #2137: Removed (private) pkg_resources.RequirementParseError, now replaced by \ 
packaging.requirements.InvalidRequirement. Kept the name for compatibility, but \ 
users should catch InvalidRequirement instead.
* #2180: Update vendored packaging in pkg_resources to 19.2.
* #2199: Fix exception causes all over the codebase by using ``raise \ 
new_exception from old_exception``