Update hacking for Python3

The repo is Python 3 now, so update hacking to version 3.0 which
supports Python 3.

Fix problems found.

Change-Id: I6bd9fdee0ee275e4d9d3fcaf96c1512933ce35a6

test-requirements.txt

@@ -4,7 +4,7 @@
 
 coverage!=4.4,>=4.0 # Apache-2.0
 fixtures>=3.0.0 # Apache-2.0/BSD
-hacking>=1.1.0,<1.2.0 # Apache-2.0
+hacking>=3.0,<3.1.0 # Apache-2.0
 mock>=2.0.0 # BSD
 oslotest>=3.2.0 # Apache-2.0
 python-subunit>=1.0.0 # Apache-2.0/BSD

tox.ini

@@ -68,7 +68,7 @@ commands = oslo_debug_helper -t watcherclient/tests/unit {posargs}
 # E123, E125 skipped as they are invalid PEP-8.
 show-source = True
 enable-extensions = H203,H106
-ignore = E123,E125
+ignore = E123,E125,W504
 builtins = _
 exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build
 

watcherclient/exceptions.py

@@ -71,6 +71,7 @@ class AmbiguousAuthSystem(exceptions.ClientException):
     """Could not obtain token and endpoint using provided credentials."""
     pass
 
+
 # Alias for backwards compatibility
 AmbigiousAuthSystem = AmbiguousAuthSystem