test_typeguesser.TestDoctypes.testGuessNumber fails with python 3.6

[mwhudson]

$ python3.6 setup.py test
...
======================================================================
ERROR: testGuessNumber (test_typeguesser.TestDoctypes)
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Traceback (most recent call last):
  File "/opt/opensource/deb/py36/python-tldp/tests/test_typeguesser.py", line 65, in testGuessNumber
    self.assertIsNone(guess(7))
  File "/opt/opensource/deb/py36/python-tldp/tldp/typeguesser.py", line 59, in guess
    stem, ext = os.path.splitext(fname)
  File "/usr/lib/python3.6/posixpath.py", line 120, in splitext
    p = os.fspath(p)
TypeError: expected str, bytes or os.PathLike object, not int

----------------------------------------------------------------------
Ran 128 tests in 1.282s

FAILED (errors=1)