Updated openstack/openstack
Project: openstack/oslo-incubator  66924eb7b1e5ea03174629f3a124d29299f26d10

cfgfilter: use some testtools helpers

We can use assertIsNone(), assertIn() and assertNotIn() in place of
assertTrue().

Change-Id: If7147629ba2dfc1f381d94482029c793f020f37f