gh-142836: Avoid /proc fd pipes on Solaris

[jaraco]

Summary

• skip using /proc/self/fd for pdb anonymous-pipe tests on Solaris, where opening those entries raises EACCES
• refactor fd-directory detection to dedicated helpers and prefer /dev/fd on affected systems
• add NEWS entry for the test fix

Issue

• fixes test_pdb failures on Solaris following realpath fixes #142836

[miss-islington-app]

Thanks @jaraco for the PR 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14.
🐍🍒⛏🤖

[bedevere-app]

GH-142854 is a backport of this pull request to the 3.14 branch.

[bedevere-app]

GH-142855 is a backport of this pull request to the 3.13 branch.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 Windows Server 2022 NoGIL 3.14 (tier-1) has failed when building commit 0613717.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1717/builds/858) and take a look at the build logs.
4. Check if the failure is related to this commit (0613717) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1717/builds/858

Summary of the results of the build (if available):

Click to see traceback logs

remote: Enumerating objects: 18, done.        
remote: Counting objects:   5% (1/18)        
remote: Counting objects:  11% (2/18)        
remote: Counting objects:  16% (3/18)        
remote: Counting objects:  22% (4/18)        
remote: Counting objects:  27% (5/18)        
remote: Counting objects:  33% (6/18)        
remote: Counting objects:  38% (7/18)        
remote: Counting objects:  44% (8/18)        
remote: Counting objects:  50% (9/18)        
remote: Counting objects:  55% (10/18)        
remote: Counting objects:  61% (11/18)        
remote: Counting objects:  66% (12/18)        
remote: Counting objects:  72% (13/18)        
remote: Counting objects:  77% (14/18)        
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remote: Counting objects:  88% (16/18)        
remote: Counting objects:  94% (17/18)        
remote: Counting objects: 100% (18/18)        
remote: Counting objects: 100% (18/18), done.        
remote: Compressing objects:  10% (1/10)        
remote: Compressing objects:  20% (2/10)        
remote: Compressing objects:  30% (3/10)        
remote: Compressing objects:  40% (4/10)        
remote: Compressing objects:  50% (5/10)        
remote: Compressing objects:  60% (6/10)        
remote: Compressing objects:  70% (7/10)        
remote: Compressing objects:  80% (8/10)        
remote: Compressing objects:  90% (9/10)        
remote: Compressing objects: 100% (10/10)        
remote: Compressing objects: 100% (10/10), done.        
remote: Total 10 (delta 7), reused 2 (delta 0), pack-reused 0 (from 0)        
From https://github.com/python/cpython
 * branch                    3.14       -> FETCH_HEAD
Note: switching to '06137178b0675f986ef6091b1f0990ec63b94955'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by switching back to a branch.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -c with the switch command. Example:

  git switch -c <new-branch-name>

Or undo this operation with:

  git switch -

Turn off this advice by setting config variable advice.detachedHead to false

HEAD is now at 06137178b06 [3.14] gh-142836: Avoid /proc fd pipes on Solaris (GH-142853) (#142854)
Switched to and reset branch '3.14'

Could Not Find C:\Users\Administrator\buildarea\3.14.itamaro-win64-srv-22-aws.x64.nogil\build\Lib\*.pyc
The system cannot find the file specified.
Could Not Find C:\Users\Administrator\buildarea\3.14.itamaro-win64-srv-22-aws.x64.nogil\build\PCbuild\python*.zip

The system cannot find the file specified.
Could Not Find C:\Users\Administrator\buildarea\3.14.itamaro-win64-srv-22-aws.x64.nogil\build\PCbuild\python*.zip

[jaraco]

Confirmed - the buildbot failure was in the build, so not possibly related to this change.