[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.
Trivial fix
Change-Id: I5b6ac7d99f0689843eb98cb3e9b9b10531322640