bpo-33635: Handling Bad file descriptor in Path.is_file and related.

[spodym]

In macOS stat on some file descriptors will result in bad file descriptor OSError. This PR is guarding agains this exception in is_dir, is_file and similar methods. DirEntry.is_dir can also throw this exception so I have extended _RecursiveWildcardSelector._iterate_directories with the same error ignoring pattern.

(default) ➜  cpython git:(fix-issue-33635) ls /dev/fd
0 1 2 3 4
(default) ➜  cpython git:(fix-issue-33635) stat /dev/fd/3
stat: /dev/fd/3: stat: Bad file descriptor
(default) ➜  cpython git:(fix-issue-33635) python
Python 3.6.4 (default, Jan  6 2018, 11:51:59)
[GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.39.2)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import pathlib
>>> pathlib.Path('/dev/fd/3').is_file()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/pathlib.py", line 1340, in is_file
    return S_ISREG(self.stat().st_mode)
  File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/pathlib.py", line 1136, in stat
    return self._accessor.stat(self)
  File "/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/pathlib.py", line 387, in wrapped
    return strfunc(str(pathobj), *args)
OSError: [Errno 9] Bad file descriptor: '/dev/fd/3'

https://bugs.python.org/issue33635

[the-knights-who-say-ni]

Hello, and thanks for your contribution!

I'm a bot set up to make sure that the project can legally accept your contribution by verifying you have signed the PSF contributor agreement (CLA).

Unfortunately we couldn't find an account corresponding to your GitHub username on bugs.python.org (b.p.o) to verify you have signed the CLA (this might be simply due to a missing "GitHub Name" entry in your b.p.o account settings). This is necessary for legal reasons before we can look at your contribution. Please follow the steps outlined in the CPython devguide to rectify this issue.

When your account is ready, please add a comment in this pull request
and a Python core developer will remove the CLA not signed label
to make the bot check again.

You can check yourself
to see if the CLA has been received.

Thanks again for your contribution, we look forward to reviewing it!

[zooba]

@spodym Just need to add the NEWS item. Click on "Details" next to the failed check for instructions on how to use blurb to add it.

[spodym]

@zooba Hi! :) Is there anything more to improve on in this PR?

[zooba]

@spodym Nope! Sorry for leaving this so long, and thanks for the work!

[miss-islington]

Thanks @spodym for the PR, and @zooba for merging it 🌮🎉.. I'm working now to backport this PR to: 3.7.
🐍🍒⛏🤖

[bedevere-bot]

GH-8960 is a backport of this pull request to the 3.7 branch.