attribute. Was throwing AttributeError before. Discovered when running
test_builtin against importlib.
This exception change is specific to importlib.__import__() and does not apply to
import_module() as it is being done for compatibility reasons only.
The file must be run using runpy. Certain tests are currently excluded from
being run as they have known failures based on golden value checks that fail
for various reasons (typically because __loader__ is not expected to be set on
modules). Running the tests with this file does discover some incompatibilites
in importlib that will be fixed in the near future (as noted currently in the
docstring).