Ah - the test used to do t.join(NUMTASKS)!  That's just bizarre ;-)

I believe I can repair that too (well - there was never a _guarantee_ that waiting 10 seconds would be long enough), but I'll wait until this all settles down.

join() and is_alive() are too complicated now, because of the 2-step dance to check whether the thread is done:  we have both an Event (_stopped) and a lock (_tstate_lock) to check now.  The Event doesn't serve a purpose anymore:  it's almost always uninteresting to know _just_ that the Python part of the thread has ended.  The only exception I can see is the perverse case of joining the main thread done in some of the tests (in that case we have to claim the main thread is done even though its tstate is still active).

Anyway, after getting rid of the Event it should be dead easy to make join(10) "appear to work the same as before, despite that it never really worked ;-)".