bpo-42053: fixed fwalk incorrect boolean test for non-fd arguments

[AliyevH]

https://bugs.python.org/issue42053

[serhiy-storchaka]

Please add a test (calling fwalk() with an object implementing __index__).

The NEWS entry is also required.

[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.

[AliyevH]

I have made the requested changes; please review again

[bedevere-bot]

Thanks for making the requested changes!

@serhiy-storchaka: please review the changes made to this pull request.

[akulakov]

It looks like we don't have a test for fwalk(top=fd) where fd would be a valid fd obj that fwalk() can successfully use. It might be nice to add a test for that because the current test would logically build on top of that, as a non-int obj implementing __index__ is meant to be usable as an fd, as implied by current code (and I assume that would actually work).

[AliyevH]

@akulakov thanks for review.
You suggest to rewrite logic of test? sorry didn't understand. Can you please provide more information?

@serhiy-storchaka. Can you please review too?

[akulakov]

@AliyevH fwalk doesn't seem to be working for valid fd in my testing:

[ins] In [69]: fw=os.fwalk(fd, follow_symlinks=True)

[ins] In [70]: list(fw)

TypeError: open: path should be string, bytes or os.PathLike, not int

[serhiy-storchaka]

I confirm that fwalk() does not support integer first argument, and never supported (this is why there are no tests). The check is misleading and should be removed.