Oops, the commit 803ddd8ce22f0de3ab42fb98a225a704c000ef06 broke the GCC job on Travis CI:
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Run tests sequentially

0:00:00 load avg: 48.91 [  1/404] test_grammar

0:00:00 load avg: 48.91 [  2/404] test_opcodes

0:00:00 load avg: 48.91 [  3/404] test_dict

0:00:00 load avg: 48.91 [  4/404] test_builtin

0:00:00 load avg: 48.91 [  5/404] test_exceptions

0:00:01 load avg: 48.91 [  6/404] test_types

0:00:01 load avg: 48.91 [  7/404] test_unittest

0:00:03 load avg: 48.91 [  8/404] test_doctest

0:00:04 load avg: 48.11 [  9/404] test_doctest2

0:00:04 load avg: 48.11 [ 10/404] test_support

0:00:07 load avg: 48.11 [ 11/404] test___all__

Traceback (most recent call last):

  File "/home/travis/build/python/cpython/Lib/test/__main__.py", line 2, in <module>

    main()

  File "/home/travis/build/python/cpython/Lib/test/libregrtest/main.py", line 585, in main

    Regrtest().main(tests=tests, **kwargs)

  File "/home/travis/build/python/cpython/Lib/test/libregrtest/main.py", line 510, in main

    self._main(tests, kwargs)

  File "/home/travis/build/python/cpython/Lib/test/libregrtest/main.py", line 536, in _main

    self.run_tests()

  File "/home/travis/build/python/cpython/Lib/test/libregrtest/main.py", line 458, in run_tests

    self.run_tests_sequential()

  File "/home/travis/build/python/cpython/Lib/test/libregrtest/main.py", line 379, in run_tests_sequential

    result = runtest(self.ns, test)

  File "/home/travis/build/python/cpython/Lib/test/libregrtest/runtest.py", line 105, in runtest

    support.set_match_tests(ns.match_tests)

  File "/home/travis/build/python/cpython/Lib/test/support/__init__.py", line 1958, in set_match_tests

    _match_test_patterns = tuple(patterns)

TypeError: 'NoneType' object is not iterable
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Attached PR 4505 fixes it.