When max_tasks_per_child is set, the ProcessPoolExecutor uses a spawn
multiprocessing context which starts a new process from scratch with a __name__
being __mp_main__ which prevents the configuration to be restored.
So in the ProcessPoolExecutor initializer the configuration is restored using
the initial options.
Closes#14843
(grafted from cb5c6667ac51818d49ca397347419a40b88768fd)
--HG--
branch : 8.0
Cédric Krier
4fca529235