test_logging hangs when run on an IPv6-only host.  (127.0.0.1 isn't even available)

test_listen_config_10_ok (test.test_logging.ConfigDictTest) ... Exception in thread Thread-3:
Traceback (most recent call last):
  File "/home/greg/oss/cpython/Lib/threading.py", line 938, in _bootstrap_inner
    self.run()
  File "/home/greg/oss/cpython/Lib/logging/config.py", line 918, in run
    server = self.rcvr(port=self.port, handler=self.hdlr,
  File "/home/greg/oss/cpython/Lib/logging/config.py", line 885, in __init__
    ThreadingTCPServer.__init__(self, (host, port), handler)
  File "/home/greg/oss/cpython/Lib/socketserver.py", line 452, in __init__
    self.server_bind()
  File "/home/greg/oss/cpython/Lib/socketserver.py", line 466, in server_bind
    self.socket.bind(self.server_address)
OSError: [Errno 99] Cannot assign requested address

possibly more, but it's hung here.

I'm preparing an IPv6-only buildbot.