[3.7] bpo-38546: Fix concurrent.futures test_ressources_gced_in_workers() (GH-17652) (GH-17655) by miss-islington · Pull Request #17656 · python/cpython

…ythonGH-17652) (pythonGH-17655)

Fix test_ressources_gced_in_workers() of test_concurrent_futures:
explicitly stop the manager to prevent leaking a child process
running in the background after the test completes.

(cherry picked from commit 673c393)
(cherry picked from commit b0eb046)

Co-authored-by: Victor Stinner <vstinner@python.org>