Upgrade setuptools.depends to importlib from depracated imp

[isidentical]

Summary

Fix;

(.venv) batuhan@x200-trisquel:~/astor$ python setup.py develop
/home/batuhan/.venv/lib/python3.8/site-packages/setuptools/depends.py:2: DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses
  import imp

Pull Request Checklist

• Changes have tests
• News fragment added in changelog.d. See documentation for details (already added about same subject

[isidentical]

apparently the error is related with pytest-dev/pytest#2506

[isidentical]

I'll change the get_code api calls to manually compiling / marshalling.

[isidentical]

All done, it is working as expectedly. No API changed.

[jaraco]

I really hate how entangled these behaviors are... and how messy the code will continue to be even after python 2.7 support is dropped. I've got a patch incoming that I think helps.

[jaraco]

Almost an hour ago, I thought I'd found a solution, but I realized used of importlib.import_module probably isn't the right usage... that the paths wasn't being honored. So I re-did the work and found that tests were failing, specifically with setuptools._imp.get_module().

I think things are working in that last commit.

@isidentical can you review this latest change and in particular explain what the code in _imp._resolve is meant to do? ...and whether it should be called in _imp.get_module?

Thanks.

[isidentical]

now it passes py27 tests (a little fix about imp.load_module

[isidentical]

py34 tests are passing (use module_from_spec if py35+)

[isidentical]

@isidentical can you review this latest change

done

explain what the code in _imp._resolve is meant to do?

when i was testing my initial patch i encountered with a case but i dont think it is needed here.

[isidentical]

Thanks

[jaraco]

Thank you. Change is releasing as v41.6.0.

[jaraco]

This change was implicated in #1896