Message 353515 - Python tracker

Fleshing out something I left implicit:  if there's a trash object T with a finalizer but we don't KNOW it's trash, we won't force-run its finalizer before delete_garbage starts either.  Then, really the same thing:  we may tp_clear some piece of trash T's finalizer needs before enough cycles are broken that T's finalizer gets run as a routine consequence of T's refcount falling to 0.