x86-64 Sierra 3.6:
http://buildbot.python.org/all/#/builders/20/builds/62

0:06:16 load avg: 3.45 [ 87/405/1] test_multiprocessing_forkserver failed -- running: test_tokenize (77 sec)
Process QueueManager-260:
Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.6.billenstein-sierra/build/Lib/multiprocessing/process.py", line 258, in _bootstrap
    self.run()
  File "/Users/buildbot/buildarea/3.6.billenstein-sierra/build/Lib/multiprocessing/process.py", line 93, in run
    self._target(*self._args, **self._kwargs)
  File "/Users/buildbot/buildarea/3.6.billenstein-sierra/build/Lib/multiprocessing/managers.py", line 539, in _run_server
    server = cls._Server(registry, address, authkey, serializer)
  File "/Users/buildbot/buildarea/3.6.billenstein-sierra/build/Lib/multiprocessing/managers.py", line 139, in __init__
    self.listener = Listener(address=address, backlog=16)
  File "/Users/buildbot/buildarea/3.6.billenstein-sierra/build/Lib/multiprocessing/connection.py", line 438, in __init__
    self._listener = SocketListener(address, family, backlog)
  File "/Users/buildbot/buildarea/3.6.billenstein-sierra/build/Lib/multiprocessing/connection.py", line 576, in __init__
    self._socket.bind(address)
OSError: [Errno 48] Address already in use
(...)

test_rlock (test.test_multiprocessing_forkserver.WithThreadsTestLock) ... ok
test_rapid_restart (test.test_multiprocessing_forkserver.WithThreadsTestManagerRestart) ... ERROR
Warning -- Dangling processes: {<ForkServerProcess(QueueManager-260, stopped[1])>}
test_boundaries (test.test_multiprocessing_forkserver.WithThreadsTestPoll) ... ok
test_dont_merge (test.test_multiprocessing_forkserver.WithThreadsTestPoll) ... ok
(...)
test_timeout (test.test_multiprocessing_forkserver.WithThreadsTestSemaphore) ... skipped 'test not appropriate for threads'
test_import (test.test_multiprocessing_forkserver._TestImportStar) ... ok
Warning -- Dangling processes: {<ForkServerProcess(QueueManager-260, stopped[1])>}

======================================================================
ERROR: test_rapid_restart (test.test_multiprocessing_forkserver.WithThreadsTestManagerRestart)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/buildbot/buildarea/3.6.billenstein-sierra/build/Lib/test/_test_multiprocessing.py", line 2508, in test_rapid_restart
    manager.start()
  File "/Users/buildbot/buildarea/3.6.billenstein-sierra/build/Lib/multiprocessing/managers.py", line 517, in start
    self._address = reader.recv()
  File "/Users/buildbot/buildarea/3.6.billenstein-sierra/build/Lib/multiprocessing/connection.py", line 250, in recv
    buf = self._recv_bytes()
  File "/Users/buildbot/buildarea/3.6.billenstein-sierra/build/Lib/multiprocessing/connection.py", line 407, in _recv_bytes
    buf = self._recv(4)
  File "/Users/buildbot/buildarea/3.6.billenstein-sierra/build/Lib/multiprocessing/connection.py", line 383, in _recv
    raise EOFError
EOFError

I didn't see this failure recently.