You must run this test as administrator.

C:\Users\vajrasky\Code\cpython>PCbuild\python.exe Lib\test\test_pathlib.py
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ERROR: test_resolve_dot (__main__.PathTest)
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Traceback (most recent call last):
  File "Lib\test\test_pathlib.py", line 1281, in test_resolve_dot
    self.assertEqual(q.resolve(), p)
  File "C:\Users\vajrasky\Code\cpython\lib\pathlib.py", line 1017, in resolve
    s = self._flavour.resolve(self)
  File "C:\Users\vajrasky\Code\cpython\lib\pathlib.py", line 179, in resolve
    return self._ext_to_normal(_getfinalpathname(s))
OSError: [WinError 123] The filename, directory name, or volume label syntax is
incorrect: 'C:\\Users\\vajrasky\\Code\\cpython\\@test_5860_tmp\\2'

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ERROR: test_resolve_dot (__main__.WindowsPathTest)
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Traceback (most recent call last):
  File "Lib\test\test_pathlib.py", line 1281, in test_resolve_dot
    self.assertEqual(q.resolve(), p)
  File "C:\Users\vajrasky\Code\cpython\lib\pathlib.py", line 1017, in resolve
    s = self._flavour.resolve(self)
  File "C:\Users\vajrasky\Code\cpython\lib\pathlib.py", line 179, in resolve
    return self._ext_to_normal(_getfinalpathname(s))
OSError: [WinError 123] The filename, directory name, or volume label syntax is
incorrect: 'C:\\Users\\vajrasky\\Code\\cpython\\@test_5860_tmp\\2'

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Windows does not like "/" in its name for the file.

Attached the patch to fix the test.