bpo-36814: ensure os.posix_spawnp handles Py_None

[tonybaloney]

https://bugs.python.org/issue36814

[tonybaloney]

Requesting review from @nanjekyejoannah

[ZackerySpytz]

I believe this change should have a test.

[tonybaloney]

@ZackerySpytz agreed, added tests

[nanjekyejoannah]

Looks fine for me. @vstinner any thoughts?

[vstinner]

You should not add tests to TestPosixSpawnP but _PosixSpawnMixin, otherwise only os.posix_spawnp() is tested, not os.posix_spawn().

Well, honestly, I would go with a PR without tests. We already have plenty of tests for posix_spawn().

If you want to add tests, please avoid setUp() and avoid hardcoding "posix_spawnp" in the test, since the tests should be run on posix_spawn and posix_spawnp.

[bedevere-bot]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

[tonybaloney]

I have made the requested changes; please review again

[bedevere-bot]

Thanks for making the requested changes!

@vstinner: please review the changes made to this pull request.