Use assertIs(Not)None to check for None

[H203] Use assertIs(Not)None to check for None (off by default) Unit
test assertions tend to give better messages for more specific
assertions. As a result, assertIsNone(...) is preferred over
assertEqual(None, ...) and assertIs(None, ...), and assertIsNotNone(...)
is preferred over assertNotEqual(None, ...) and assertIsNot(None,
...). Off by default.

More information, see:
http://docs.openstack.org/developer/hacking/#unit-tests-and-assertraises

Change-Id: I73a9ed3e145b8f36c110725d148baf1fb0aef957
diff --git a/tempest/tests/common/test_custom_matchers.py b/tempest/tests/common/test_custom_matchers.py
index 07867fc..1053d86 100644
--- a/tempest/tests/common/test_custom_matchers.py
+++ b/tempest/tests/common/test_custom_matchers.py
@@ -25,11 +25,11 @@
         matches = self.matches_matches
         mismatches = self.matches_mismatches
         for candidate in matches:
-            self.assertEqual(None, matcher.match(candidate))
+            self.assertIsNone(matcher.match(candidate))
         for candidate in mismatches:
             mismatch = matcher.match(candidate)
-            self.assertNotEqual(None, mismatch)
-            self.assertNotEqual(None, getattr(mismatch, 'describe', None))
+            self.assertIsNotNone(mismatch)
+            self.assertIsNotNone(getattr(mismatch, 'describe', None))
 
     def test__str__(self):
         # [(expected, object to __str__)].