Tests are failing on Windows.

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ERROR: test_ordered_recursion (test.test_tarfile.Bz2WriteTest)
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Traceback (most recent call last):
  File "C:\py\cpython3.7\lib\unittest\mock.py", line 1191, in patched
    return func(*args, **keywargs)
  File "C:\py\cpython3.7\lib\test\test_tarfile.py", line 1152, in test_ordered_recursion
    support.unlink(os.path.join(path, "1"))
  File "C:\py\cpython3.7\lib\test\support\__init__.py", line 394, in unlink
    _unlink(filename)
  File "C:\py\cpython3.7\lib\test\support\__init__.py", line 344, in _unlink
    _waitfor(os.unlink, filename)
  File "C:\py\cpython3.7\lib\test\support\__init__.py", line 341, in _waitfor
    RuntimeWarning, stacklevel=4)
RuntimeWarning: tests may fail, delete still pending for C:\py\cpython3.7\build\test_python_8504\@test_8504_tmp-tardir\directory\1

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ERROR: test_directory_size (test.test_tarfile.GzipWriteTest)
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Traceback (most recent call last):
  File "C:\py\cpython3.7\lib\test\test_tarfile.py", line 1121, in test_directory_size
    os.mkdir(path)
FileExistsError: [WinError 183] Cannot create a file when that file already exists: 'C:\\py\\cpython3.7\\build\\test_python_8504\\@test_8504_tmp-tardir\\directory'

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ERROR: test_ordered_recursion (test.test_tarfile.GzipWriteTest)
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Traceback (most recent call last):
  File "C:\py\cpython3.7\lib\unittest\mock.py", line 1191, in patched
    return func(*args, **keywargs)
  File "C:\py\cpython3.7\lib\test\test_tarfile.py", line 1137, in test_ordered_recursion
    os.mkdir(path)
FileExistsError: [WinError 183] Cannot create a file when that file already exists: 'C:\\py\\cpython3.7\\build\\test_python_8504\\@test_8504_tmp-tardir\\directory'

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ERROR: test_directory_size (test.test_tarfile.LzmaWriteTest)
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Traceback (most recent call last):
  File "C:\py\cpython3.7\lib\test\test_tarfile.py", line 1121, in test_directory_size
    os.mkdir(path)
FileExistsError: [WinError 183] Cannot create a file when that file already exists: 'C:\\py\\cpython3.7\\build\\test_python_8504\\@test_8504_tmp-tardir\\directory'

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ERROR: test_ordered_recursion (test.test_tarfile.LzmaWriteTest)
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Traceback (most recent call last):
  File "C:\py\cpython3.7\lib\unittest\mock.py", line 1191, in patched
    return func(*args, **keywargs)
  File "C:\py\cpython3.7\lib\test\test_tarfile.py", line 1137, in test_ordered_recursion
    os.mkdir(path)
FileExistsError: [WinError 183] Cannot create a file when that file already exists: 'C:\\py\\cpython3.7\\build\\test_python_8504\\@test_8504_tmp-tardir\\directory'

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ERROR: test_directory_size (test.test_tarfile.WriteTest)
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Traceback (most recent call last):
  File "C:\py\cpython3.7\lib\test\test_tarfile.py", line 1121, in test_directory_size
    os.mkdir(path)
FileExistsError: [WinError 183] Cannot create a file when that file already exists: 'C:\\py\\cpython3.7\\build\\test_python_8504\\@test_8504_tmp-tardir\\directory'

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ERROR: test_ordered_recursion (test.test_tarfile.WriteTest)
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Traceback (most recent call last):
  File "C:\py\cpython3.7\lib\unittest\mock.py", line 1191, in patched
    return func(*args, **keywargs)
  File "C:\py\cpython3.7\lib\test\test_tarfile.py", line 1137, in test_ordered_recursion
    os.mkdir(path)
FileExistsError: [WinError 183] Cannot create a file when that file already exists: 'C:\\py\\cpython3.7\\build\\test_python_8504\\@test_8504_tmp-tardir\\directory'

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