Message 302163 - Python tracker

Oh, test_concurrent_futures.test_exception_with_success() failed on Travis CI :-(

https://ci.appveyor.com/project/python/cpython/build/3.7.0a0.6457

test_exception_with_success (test.test_concurrent_futures.FutureTests) ... Warning -- threading_cleanup() failed to cleanup 1 threads (count: 1, dangling: 2)
Dangling thread: <Thread(Thread-1, started 4012)>
Dangling thread: <_MainThread(MainThread, started 3656)>
ok