try: import threading except ImportError: threading = None # use non-threaded behaviour
But then you'd have to sprinkle the rest of the code with "if threading is not None" tests. Brett's dummy_thread is an attempt to reduce this clutter.
the problem (if there is one) is that the proposed integration may break code that uses the above pattern.
deadlocks doesn't always happen when you want them to, so it may not be obvious to developers and testers that their program isn't as reliable as it was before the upgrade.