Trying to unskip all in_app Marionette unit tests via bug 1363368 showed that on Windows we have a perma failure of TestQuitRestart.test_in_app_restart_with_callback_no_shutdown: https://treeherder.mozilla.org/#/jobs?repo=try&revision=e90a3c286a122fe22113d7ecb64b29cde4296987&selectedJob=122282059 13:41:04 ERROR - TEST-UNEXPECTED-FAIL | test_quit_restart.py TestQuitRestart.test_in_app_restart_with_callback_no_shutdown | AssertionError: "the connection to Marionette server is lost" does not match "Process has been unexpectedly closed (Exit code: 0) (Reason: Timed out waiting for connection on localhost:2828!)" 13:41:04 INFO - Traceback (most recent call last): 13:41:04 INFO - File "Z:\task_1502370070\build\venv\lib\site-packages\marionette_harness\marionette_test\testcases.py", line 156, in run 13:41:04 INFO - testMethod() 13:41:04 INFO - File "Z:\task_1502370070\build\tests\marionette\tests\testing\marionette\harness\marionette_harness\tests\unit\test_quit_restart.py", line 191, in test_in_app_restart_with_callback_no_shutdown 13:41:04 INFO - self.marionette.restart(in_app=True, callback=lambda: False) 13:41:04 INFO - TEST-INFO took 179290ms The reason is: 13:41:04 INFO - WARNING | IO Completion Port failed to signal process shutdown 13:41:04 INFO - Parent process 228 exited with children alive: 13:41:04 INFO - PIDS: 3712, 7280, 13184, 12580 13:41:04 INFO - Attempting to kill them, but no guarantee of success

The referenced test has been renamed to `test_in_app_restart_with_callback_missing_shutdown`, and unskipping is now tracked via bug 1493796.

Moving bug to Testing::Marionette Client and Harness component per bug 1815831.