Ensured all methods in setuptools.modified raise a consistant distutils.error.DistutilsError type

[Avasam]

Summary of changes

The following code should now work as expected in all cases:

from setuptools.modified import newer_pairwise_group
from distutils.error import DistutilsError

try:
    newer_pairwise_group(...)
except DistutilsError:
    pass

I'm not entirely certain my test is correct. Hopefully it should be.

Pull Request Checklist

• Changes have tests
• News fragment added in newsfragments/.
  (See documentation for details)

[abravalheri]

Suggested change

	Ensured all methods in ``setuptools.modified`` raise a consistant ``distutils.errors.DistutilsError`` type -- by :user:`Avasam`
	Ensured methods in ``setuptools.modified`` preferably raise a consistent
	``distutils.errors.DistutilsError`` type
	(except in the deprecated use case of ``SETUPTOOLS_USE_DISTUTILS=stdlib``)
	-- by :user:`Avasam`

[Avasam]

In the case of the exception (e.g. SETUPTOOLS_USE_DISTUTILS=stdlib) these methods would raise setuptools._distutils.error.DistutilsError error, right?

So maybe we have to change the news fragment a bit...

hmm, looking at my tests I think the intention was to be truly the same as distutils.errors.DistutilsError at all time, but I see how that won't be the case, unless we start wrapping _distutils methods here to catch & rethrow (let's not do that).

I think that's still an improvement for the "intended usage" (ie: not using deprecated SETUPTOOLS_USE_DISTUTILS=stdlib). But I'll need to update my tests to reflect that.

[abravalheri]

I think it is OK to say: "If you need to catch that error, please don't use the deprecated SETUPTOOLS_USE_DISTUTILS=stdlib settings", so I am good with this.