gh-113086: Add tests for os.chmod() and os.lchmod()

[serhiy-storchaka]

Also make test_copymode_symlink_to_symlink in test_shutil more strict.

• Issue: Add tests for os.chmod() and os.lchmod() #113086

[miss-islington-app]

Thanks @serhiy-storchaka for the PR 🌮🎉.. I'm working now to backport this PR to: 3.11, 3.12.
🐍🍒⛏🤖

[bedevere-app]

GH-113088 is a backport of this pull request to the 3.12 branch.

[bedevere-app]

GH-113089 is a backport of this pull request to the 3.11 branch.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot wasm32-wasi 3.x has failed when building commit b4f2c89.

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/all/#builders/1046/builds/3741) and take a look at the build logs.
4. Check if the failure is related to this commit (b4f2c89) 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/all/#builders/1046/builds/3741

Failed tests:

• test_posix

Failed subtests:

• test_chmod_file - test.test_posix.PosixTester.test_chmod_file
• test_chmod_dir - test.test_posix.PosixTester.test_chmod_dir

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

==

Click to see traceback logs

Traceback (most recent call last):
  File "/Lib/test/test_posix.py", line 970, in test_chmod_dir
    self.check_chmod(posix.chmod, target)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^
  File "/Lib/test/test_posix.py", line 952, in check_chmod
    self.assertEqual(os.stat(target).st_mode, new_mode)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: 16384 != 16530


Traceback (most recent call last):
  File "/Lib/test/test_posix.py", line 960, in test_chmod_file
    self.check_chmod(posix.chmod, os_helper.TESTFN)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Lib/test/test_posix.py", line 952, in check_chmod
    self.assertEqual(os.stat(target).st_mode, new_mode)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: 32768 != 32914

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot wasm32-wasi 3.11 has failed when building commit e4cdb74.

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/all/#builders/1047/builds/1156) and take a look at the build logs.
4. Check if the failure is related to this commit (e4cdb74) 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/all/#builders/1047/builds/1156

Failed tests:

• test_posix

Failed subtests:

• test_chmod_file - test.test_posix.PosixTester.test_chmod_file
• test_chmod_dir - test.test_posix.PosixTester.test_chmod_dir

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

==

Click to see traceback logs

Traceback (most recent call last):
  File "/Lib/test/test_posix.py", line 960, in test_chmod_file
    self.check_chmod(posix.chmod, os_helper.TESTFN)
  File "/Lib/test/test_posix.py", line 952, in check_chmod
    self.assertEqual(os.stat(target).st_mode, new_mode)
AssertionError: 32768 != 32914


Traceback (most recent call last):
  File "/Lib/test/test_posix.py", line 970, in test_chmod_dir
    self.check_chmod(posix.chmod, target)
  File "/Lib/test/test_posix.py", line 952, in check_chmod
    self.assertEqual(os.stat(target).st_mode, new_mode)
AssertionError: 16384 != 16530

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot wasm32-wasi 3.12 has failed when building commit 0bd1899.

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/all/#builders/1124/builds/532) and take a look at the build logs.
4. Check if the failure is related to this commit (0bd1899) 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/all/#builders/1124/builds/532

Failed tests:

• test_posix

Failed subtests:

• test_chmod_file - test.test_posix.PosixTester.test_chmod_file
• test_chmod_dir - test.test_posix.PosixTester.test_chmod_dir

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

==

Click to see traceback logs

Traceback (most recent call last):
  File "/Lib/test/test_posix.py", line 960, in test_chmod_file
    self.check_chmod(posix.chmod, os_helper.TESTFN)
  File "/Lib/test/test_posix.py", line 952, in check_chmod
    self.assertEqual(os.stat(target).st_mode, new_mode)
AssertionError: 32768 != 32914


Traceback (most recent call last):
  File "/Lib/test/test_posix.py", line 970, in test_chmod_dir
    self.check_chmod(posix.chmod, target)
  File "/Lib/test/test_posix.py", line 952, in check_chmod
    self.assertEqual(os.stat(target).st_mode, new_mode)
AssertionError: 16384 != 16530