If we were waiting, and then exiting due to timeout, we still have to
recheck the condition protected by the condition variable/mutex in order
to get back to a consistent state. In this case, the queue was locked
with mp_dispatch_lock(), and mp_dispatch_queue_process() got to return
without waiting for unlock.
Also caused commit 8716c2e8. Probably an argument for replacing the
dispatch queue by a simple mutex.
wm4
17e3e800e1