To work around the included distutils in setuptools not supporting
we changed the default of SETUPTOOLS_USE_DISTUTILS to make it use
the stdlib distutils, which supports mingw obviously.
With Python 3.12 no longer providing a distutils this no longer works.
Instead use the pending distutils PR which adds mingw support to
the new external distutils in https://github.com/pypa/distutils/pull/184
and patch the vendored version in setuptools.
This makes Python 3.12 work (outside of venvs and isolated build envs at least)
and also gives the PR some real world testing when we build MSYS2 Python
packages with it.
If this breaks something you can set SETUPTOOLS_USE_DISTUTILS=stdlib to
get the old behaviour, but please report any issues either way.
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