The root issue is likely related to "RuntimeWarning: tests may fail, unable to create temporary directory '/buildbot/tmp/tmpdir/test_python_28144': [Errno 17] File exists".

I don't know if a previous buildbot run forgot to remove this directory, or if it's a race condition in test_regrtest?

https://buildbot.python.org/all/#/builders/103/builds/2679

FAIL: test_list_cases (test.test_regrtest.ArgsTestCase)
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Traceback (most recent call last):
  File "/buildbot/buildarea/cpython/3.x.ware-gentoo-x86.installed/build/target/lib/python3.9/test/test_regrtest.py", line 915, in test_list_cases
    self.assertEqual(output.splitlines(), all_methods)
AssertionError: Lists differ: ['tes[73 chars]hod2', "/buildbot/buildarea/cpython/3.x.ware-g[307 chars]th:'] != ['tes[73 chars]hod2']

First list contains 2 additional elements.
First extra element 2:
"/buildbot/buildarea/cpython/3.x.ware-gentoo-x86.installed/build/target/lib/python3.9/test/support/__init__.py:1058: RuntimeWarning: tests may fail, unable to create temporary directory '/buildbot/tmp/tmpdir/test_python_28144': [Errno 17] File exists: '/buildbot/tmp/tmpdir/test_python_28144'"

  ['test_regrtest_noop8.Tests.test_method1',
-  'test_regrtest_noop8.Tests.test_method2',
?                                          ^

+  'test_regrtest_noop8.Tests.test_method2']
?                                          ^

-  '/buildbot/buildarea/cpython/3.x.ware-gentoo-x86.installed/build/target/lib/python3.9/test/support/__init__.py:1058: '
-  'RuntimeWarning: tests may fail, unable to create temporary directory '
-  "'/buildbot/tmp/tmpdir/test_python_28144': [Errno 17] File exists: "
-  "'/buildbot/tmp/tmpdir/test_python_28144'",
-  '  with temp_dir(path=name, quiet=quiet) as temp_path:']

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