There is a race condition in FAIL: test_signal_handling_args (test.test_asyncio.test_events.KqueueEventLoopTests) in macOS:

https://buildbot.python.org/all/#/builders/147/builds/546/steps/4/logs/stdio

======================================================================
FAIL: test_signal_handling_args (test.test_asyncio.test_events.KqueueEventLoopTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.7.billenstein-sierra/build/Lib/test/test_asyncio/test_events.py", line 595, in test_signal_handling_args
    self.assertEqual(caught, 1)
AssertionError: 0 != 1

It seems that SIGALRM is never received in the 0.5 seconds of timeout:

    def test_signal_handling_args(self):
        some_args = (42,)
        caught = 0

        def my_handler(*args):
            nonlocal caught
            caught += 1
            self.assertEqual(args, some_args)

        self.loop.add_signal_handler(signal.SIGALRM, my_handler, *some_args)

        signal.setitimer(signal.ITIMER_REAL, 0.1, 0)  # Send SIGALRM once.
        self.loop.call_later(0.5, self.loop.stop)
        self.loop.run_forever()
        self.assertEqual(caught, 1)

Maybe we should set up a much bigger timeout and make the handle stop the event loop.

New changeset 5471420faa84519530f29b08f2b042b2288e3e96 by Pablo Galindo in branch 'master':
bpo-35601: Alleviate race condition when waiting for SIGALRM in test_asyncio (GH-11337)
https://github.com/python/cpython/commit/5471420faa84519530f29b08f2b042b2288e3e96

New changeset 8f9228dd3a37c98876c9c8ff7fb0042650303474 by Miss Islington (bot) in branch '3.7':
bpo-35601: Alleviate race condition when waiting for SIGALRM in test_asyncio (GH-11337)
https://github.com/python/cpython/commit/8f9228dd3a37c98876c9c8ff7fb0042650303474

I am going to close this one as the only branch left is 3.6 and is on security fixes only.

New changeset 7eef540ab89e426b622373f43713521876447f2f by Ned Deily (Miss Islington (bot)) in branch '3.6':
bpo-35601: Alleviate race condition when waiting for SIGALRM in test_asyncio (GH-11337) (GH-11348)
https://github.com/python/cpython/commit/7eef540ab89e426b622373f43713521876447f2f