Fix for multiprocessing.queues.Queue not closing properly if no put.
See pypy issue #3372 and CPython issue #42752 for context. This fixes the fact that close won't close the write pipe unless something had already been put in the Queue. --HG-- branch : py3_7_mp_queue_close_fix
branch/py3_7_mp_queue_close_fix in 8 minutes and 6 seconds (queued for 1 second)2 jobs for