Many plases in tests code use assertEqual(AA, None),
the same with True and False and negatives of such comparisons.
As comparison to singletons must use `is` operator, appropriate usage
is assertIs, assertIsNot, assertIsNone, assertIsNotNone
These assertions are provided by the `testtools` package,
so this change is not breaking backward compatibility with Python 2.6
This second patch inlcudes the other half of the files touched by these
changes to ease the review.
Change-Id: I9965ae158f3e0dc49b93b9357a32a302ac7dc735
Closes-Bug: #1259023
594dd453a8