Victor, this issue is reproducible on Linux. I reproduced it on my WSL. And I've identified the issue is in test_close_kill_running. The patch for resolving the crash in bpo-38323 can be the cause of the newly introduced hang. test_close_kill_running is running and passing and again it is running all over again infinitely. And extending the buildbot timer may not help since it seems it's running infinitely. Even if we look at the buildbot log there is no sign of crash but suddenly buildbot says "timeout!".