Fails test under python 3.6

Under Py 3.6, here's failed test. It does work with Py 3.5 and 2.7 though.

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FAIL: mox3.tests.test_mox.RegexTest.testReprWithFlags
mox3.tests.test_mox.RegexTest.testReprWithFlags
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_StringException: Traceback (most recent call last):
  File "/home/zigo/sources/openstack/pike/python-mox3/build-area/python-mox3-0.23.0/mox3/tests/test_mox.py", line 319, in testReprWithFlags
    self.assertTrue(repr(mox.Regex(r"a\s+b", flags=4)) ==
  File "/home/zigo/sources/openstack/pike/python-mox3/build-area/python-mox3-0.23.0/mox3/mox.py", line 1530, in __init__
    self.regex = re.compile(pattern, flags=flags)
  File "/usr/lib/python3.6/re.py", line 233, in compile
    return _compile(pattern, flags)
  File "/usr/lib/python3.6/re.py", line 301, in _compile
    p = sre_compile.compile(pattern, flags)
  File "/usr/lib/python3.6/sre_compile.py", line 562, in compile
    p = sre_parse.parse(p, flags)
  File "/usr/lib/python3.6/sre_parse.py", line 865, in parse
    p.pattern.flags = fix_flags(str, p.pattern.flags)
  File "/usr/lib/python3.6/sre_parse.py", line 832, in fix_flags
    raise ValueError("cannot use LOCALE flag with a str pattern")
ValueError: cannot use LOCALE flag with a str pattern