TestArbitraryPackageAttack TearDownClass failure #1119

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70ERROR: tearDownClass (test_arbitrary_package_attack.TestArbitraryPackageAttack)
71----------------------------------------------------------------------
72Traceback (most recent call last):
73  File "C:\projects\tuf\tests\test_arbitrary_package_attack.py", line 101, in tearDownClass
74    shutil.rmtree(cls.temporary_directory)
75  File "C:\Python38\lib\shutil.py", line 730, in rmtree
76    return _rmtree_unsafe(path, onerror)
77  File "C:\Python38\lib\shutil.py", line 603, in _rmtree_unsafe
78    _rmtree_unsafe(fullname, onerror)
79  File "C:\Python38\lib\shutil.py", line 603, in _rmtree_unsafe
80    _rmtree_unsafe(fullname, onerror)
81  File "C:\Python38\lib\shutil.py", line 603, in _rmtree_unsafe
82    _rmtree_unsafe(fullname, onerror)
83  File "C:\Python38\lib\shutil.py", line 608, in _rmtree_unsafe
84    onerror(os.unlink, fullname, sys.exc_info())
85  File "C:\Python38\lib\shutil.py", line 606, in _rmtree_unsafe
86    os.unlink(fullname)
87PermissionError: [WinError 32] The process cannot access the file because it is being used by another process: 'C:\\projects\\tuf\\tests\\tmpmsjfh32h\\TestArbitraryPackageAttack_axb40vsy\\repository\\targets\\file1.txt'

  @classmethod
  def tearDownClass(cls):
    # tearDownModule() is called after all the test cases have run.
    # http://docs.python.org/2/library/unittest.html#class-and-module-fixtures

    # Remove the temporary repository directory, which should contain all the
    # metadata, targets, and key files generated of all the test cases.
    shutil.rmtree(cls.temporary_directory)

    # Kill the SimpleHTTPServer process.
    if cls.server_process.returncode is None:
      logger.info('Server process ' + str(cls.server_process.pid) + ' terminated.')
      cls.server_process.kill()
      cls.server_process.wait()