* connect()-ing an AF_UNIX socket can hang indefinitely
  if the server is not actively accept()-ing connections; see
  https://cygwin.com/ml/cygwin/2017-01/msg00054.html This issue is
  worked around explicitly in the tests, but not generally in asyncore
  (as the only known general workaround breaks SO_PEERCRED queries).
  It's also something of a corner-case which won't affect non-test code
  often.

Unfortunately it's harder to work around in these tests since socket creation
is significantly more buried in the code being tested.  Better to just skip
them.