On Python 2, importlib.import_module accepts bytes or unicode.
Future.set_running_or_notify_cancel returns a bool, not None. See commit 13bcc79c12, where this problem was fixed for Python 2.
13bcc79c12
* Add missing methods to Python 2 concurrent.futures Future.exception_info() and Future.set_exception_info() are methods present only in the Python 2 backport of concurrent.futures. * Mark timeout args as optional
Daniel Li