gh-110160: Fix flaky test_find_periodic_pattern in string_tests

[sobolevn]

• Issue: test_userstring: test_find_periodic_pattern() failed on GHA Hypothesis tests on Ubuntu #110160

[vstinner]

LGTM.

[miss-islington]

Thanks @sobolevn for the PR, and @vstinner for merging it 🌮🎉.. I'm working now to backport this PR to: 3.12.
🐍🍒⛏🤖

[bedevere-app]

GH-110182 is a backport of this pull request to the 3.12 branch.

[miss-islington]

Thanks @sobolevn for the PR, and @vstinner for merging it 🌮🎉.. I'm working now to backport this PR to: 3.11.
🐍🍒⛏🤖

[miss-islington]

Sorry, @sobolevn and @vstinner, I could not cleanly backport this to 3.11 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 06faa9a39bd93c5e7999d52b52043ecdd0774dac 3.11

[bedevere-app]

GH-110183 is a backport of this pull request to the 3.11 branch.

[vstinner]

Merged, thanks. I backported the change manually to 3.11 to fix a merge conflict.

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot aarch64 Fedora Stable 3.x has failed when building commit 06faa9a.

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/125/builds/4597) and take a look at the build logs.
4. Check if the failure is related to this commit (06faa9a) 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/125/builds/4597

Failed tests:

• test.test_concurrent_futures.test_deadlock

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

==

Click to see traceback logs

remote: Enumerating objects: 5, done. remote: Counting objects: 20% (1/5) remote: Counting objects: 40% (2/5) remote: Counting objects: 60% (3/5) remote: Counting objects: 80% (4/5) remote: Counting objects: 100% (5/5) remote: Counting objects: 100% (5/5), done. remote: Compressing objects: 20% (1/5) remote: Compressing objects: 40% (2/5) remote: Compressing objects: 60% (3/5) remote: Compressing objects: 80% (4/5) remote: Compressing objects: 100% (5/5) remote: Compressing objects: 100% (5/5), done. remote: Total 5 (delta 0), reused 1 (delta 0), pack-reused 0 
From https://github.com/python/cpython
* branch main -> FETCH_HEAD
Note: switching to '06faa9a39bd93c5e7999d52b52043ecdd0774dac'.
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Turn off this advice by setting config variable advice.detachedHead to false
HEAD is now at 06faa9a39b gh-110160: Fix flaky `test_find_periodic_pattern` in `string_tests` (#110170)
Switched to and reset branch 'main'
../Objects/longobject.c: In function ‘long_format_binary’:
../Objects/longobject.c:2120:13: warning: ‘kind’ may be used uninitialized [-Wmaybe-uninitialized]
2120 | else if (kind == PyUnicode_1BYTE_KIND) {
|^
../Objects/longobject.c:1996:9: note: ‘kind’ was declared here
1996 | int kind;
|^~~~../Objects/longobject.c: In function ‘long_to_decimal_string_internal’:
../Objects/longobject.c:1943:13: warning: ‘kind’ may be used uninitialized [-Wmaybe-uninitialized]
1943 | else if (kind == PyUnicode_1BYTE_KIND) {
|^
../Objects/longobject.c:1767:9: note: ‘kind’ was declared here
1767 | int kind;
|^~~~make: *** [Makefile:2020: buildbottest] Error 5