ISsue #14988: restore Python 2's behavior of raising ImportError when unable to load pyexpat, instead of a SystemError/RuntimeError
ISsue #14988: restore Python 2's behavior of raising ImportError when unable to load pyexpat, instead of a SystemError/RuntimeError

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