As discussed briefly on python-dev, add Pending Deprecation Warning when a string exception is raised.  Note that raising string exceptions is deprecated in an exception message.
As discussed briefly on python-dev, add Pending Deprecation Warning
when a string exception is raised.  Note that raising string exceptions
is deprecated in an exception message.

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