Add a bunch of tests for extended dict.update() where the argument is a non-dictionary mapping object.  Include tests for several expected failure modes.
Add a bunch of tests for extended dict.update() where the argument is
a non-dictionary mapping object.  Include tests for several expected
failure modes.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator