GH-119169: Simplify os.walk() exception handling

[barneygale]

Handle errors from os.scandir() and ScandirIterator similarly, which lets us loop over directory entries with for.

$ ./python -m timeit -s 'import os' 'list(os.walk("."))'
5 loops, best of 5: 41.5 msec per loop
5 loops, best of 5: 40.1 msec per loop
# --> 3.5% faster

• Issue: Improve performance of os.walk() #119169

[serhiy-storchaka]

LGTM.

This is not so much optimization as simplification.

[barneygale]

Thanks Serhiy

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 RHEL8 LTO + PGO 3.x has failed when building commit db00fee.

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/568/builds/6911) and take a look at the build logs.
4. Check if the failure is related to this commit (db00fee) 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/568/builds/6911

Failed tests:

• test_smtplib

Failed subtests:

• test_with_statement_QUIT_failure - test.test_smtplib.SMTPSimTests.test_with_statement_QUIT_failure
• test_with_statement - test.test_smtplib.SMTPSimTests.test_with_statement

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

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.lto-pgo/build/Lib/test/test_smtplib.py", line 1243, in test_with_statement_QUIT_failure
    smtp.noop()
    ~~~~~~~~~^^
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.lto-pgo/build/Lib/smtplib.py", line 523, in noop
    return self.docmd("noop")
           ~~~~~~~~~~^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.lto-pgo/build/Lib/smtplib.py", line 430, in docmd
    return self.getreply()
           ~~~~~~~~~~~~~^^
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.lto-pgo/build/Lib/smtplib.py", line 403, in getreply
    raise SMTPServerDisconnected("Connection unexpectedly closed")
smtplib.SMTPServerDisconnected: Connection unexpectedly closed


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.lto-pgo/build/Lib/test/test_smtplib.py", line 1233, in test_with_statement
    code, message = smtp.noop()
                    ~~~~~~~~~^^
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.lto-pgo/build/Lib/smtplib.py", line 523, in noop
    return self.docmd("noop")
           ~~~~~~~~~~^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.lto-pgo/build/Lib/smtplib.py", line 430, in docmd
    return self.getreply()
           ~~~~~~~~~~~~~^^
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-x86_64.lto-pgo/build/Lib/smtplib.py", line 403, in getreply
    raise SMTPServerDisconnected("Connection unexpectedly closed")
smtplib.SMTPServerDisconnected: Connection unexpectedly closed

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 RHEL8 FIPS Only Blake2 Builtin Hash 3.x has failed when building commit db00fee.

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/469/builds/8522) and take a look at the build logs.
4. Check if the failure is related to this commit (db00fee) 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/469/builds/8522

Failed tests:

• test_smtplib

Failed subtests:

• test_with_statement_QUIT_failure - test.test_smtplib.SMTPSimTests.test_with_statement_QUIT_failure
• test_with_statement - test.test_smtplib.SMTPSimTests.test_with_statement

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

==

Click to see traceback logs

Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-fips-x86_64.no-builtin-hashes-except-blake2/build/Lib/test/test_smtplib.py", line 1243, in test_with_statement_QUIT_failure
    smtp.noop()
    ~~~~~~~~~^^
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-fips-x86_64.no-builtin-hashes-except-blake2/build/Lib/smtplib.py", line 523, in noop
    return self.docmd("noop")
           ~~~~~~~~~~^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-fips-x86_64.no-builtin-hashes-except-blake2/build/Lib/smtplib.py", line 430, in docmd
    return self.getreply()
           ~~~~~~~~~~~~~^^
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-fips-x86_64.no-builtin-hashes-except-blake2/build/Lib/smtplib.py", line 403, in getreply
    raise SMTPServerDisconnected("Connection unexpectedly closed")
smtplib.SMTPServerDisconnected: Connection unexpectedly closed


Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-fips-x86_64.no-builtin-hashes-except-blake2/build/Lib/test/test_smtplib.py", line 1233, in test_with_statement
    code, message = smtp.noop()
                    ~~~~~~~~~^^
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-fips-x86_64.no-builtin-hashes-except-blake2/build/Lib/smtplib.py", line 523, in noop
    return self.docmd("noop")
           ~~~~~~~~~~^^^^^^^^
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-fips-x86_64.no-builtin-hashes-except-blake2/build/Lib/smtplib.py", line 430, in docmd
    return self.getreply()
           ~~~~~~~~~~~~~^^
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL8-fips-x86_64.no-builtin-hashes-except-blake2/build/Lib/smtplib.py", line 403, in getreply
    raise SMTPServerDisconnected("Connection unexpectedly closed")
smtplib.SMTPServerDisconnected: Connection unexpectedly closed