bpo-30356: Fix test_mymanager_context() of multiprocessing (GH-7968)

bpo-30356: Fix test_mymanager_context() of multiprocessing (GH-7968) · python/cpython@34f2935

Original file line number	Diff line number	Diff line change
`@@ -2666,7 +2666,9 @@ def test_mymanager(self):`
`2666`	`2666`	`def test_mymanager_context(self):`
`2667`	`2667`	`with MyManager() as manager:`
`2668`	`2668`	`self.common(manager)`
`2669`		`-self.assertEqual(manager._process.exitcode, 0)`
	`2669`	`+# bpo-30356: BaseManager._finalize_manager() sends SIGTERM`
	`2670`	`+# to the manager process if it takes longer than 1 second to stop.`
	`2671`	`+self.assertIn(manager._process.exitcode, (0, -signal.SIGTERM))`
`2670`	`2672`
`2671`	`2673`	`def test_mymanager_context_prestarted(self):`
`2672`	`2674`	`manager = MyManager()`