WindmillLayer tests occasionally hit a timeout in client.open

WindmillLayer is still unreliable, although now with a timeout instead of a hang. It always happens with this same client.open traceback, but in different tests.

Traceback (most recent call last):
  File "/srv/buildbot/slaves/launchpad/lucid-devel/build/orig_sourcecode/eggs/testtools-0.9.8-py2.6.egg/testtools/runtest.py", line 169, in _run_user
    return fn(*args, **kwargs)
  File "/srv/buildbot/slaves/launchpad/lucid-devel/build/orig_sourcecode/eggs/testtools-0.9.8-py2.6.egg/testtools/testcase.py", line 499, in _run_test_method
    return self._get_test_method()()
  File "/srv/buildbot/slaves/launchpad/lucid-devel/build/lib/lp/code/windmill/tests/test_branch_popupdiff.py", line 124, in test_newly_linked_branch_diff_popup
    '/bugs/%d' % bug.id, objs['eric'])
  File "/srv/buildbot/slaves/launchpad/lucid-devel/build/lib/lp/testing/__init__.py", line 810, in getClientForPerson
    return self.getClientFor(url, user=user)
  File "/srv/buildbot/slaves/launchpad/lucid-devel/build/lib/lp/testing/__init__.py", line 801, in getClientFor
    client.open(url=obj_url)
  File "/srv/buildbot/slaves/launchpad/lucid-devel/build/orig_sourcecode/eggs/windmill-1.5pre_deryck-py2.6.egg/windmill/authoring/__init__.py", line 161, in __call__
    result = self.exec_method(self.action_name, **kwargs)
  File "/srv/buildbot/slaves/launchpad/lucid-devel/build/orig_sourcecode/eggs/windmill-1.5pre_deryck-py2.6.egg/windmill/authoring/__init__.py", line 228, in _exec_test
    result = self._method_proxy.execute_test({'method':test_name, 'params':kwargs})
  File "/srv/buildbot/slaves/launchpad/lucid-devel/build/orig_sourcecode/eggs/windmill-1.5pre_deryck-py2.6.egg/windmill/tools/json_tools.py", line 60, in __call__
    return self.call(json.dumps(request))
  File "/srv/buildbot/slaves/launchpad/lucid-devel/build/orig_sourcecode/eggs/windmill-1.5pre_deryck-py2.6.egg/windmill/tools/json_tools.py", line 130, in __request
    response = self.__transport.request(request)
  File "/srv/buildbot/slaves/launchpad/lucid-devel/build/orig_sourcecode/eggs/windmill-1.5pre_deryck-py2.6.egg/windmill/tools/json_tools.py", line 98, in request
    self.response = connection.getresponse()
  File "/usr/lib/python2.6/httplib.py", line 986, in getresponse
    response.begin()
  File "/usr/lib/python2.6/httplib.py", line 391, in begin
    version, status, reason = self._read_status()
  File "/usr/lib/python2.6/httplib.py", line 349, in _read_status
    line = self.fp.readline()
  File "/usr/lib/python2.6/socket.py", line 397, in readline
    data = recv(1)
timeout: timed out