lp.bugs.tests.test_bugchanges.TestBugChanges.test_change_information_type_using_api fails intermittently/rarely in parallel tests (again)

bug 996773 is happening again. The previous fix for that bug is in place, but, as before, running these two tests in order (--load-list) will cause the test to fail.

lp.services.webservice.tests.test_wadl_generation.SmokeTestWadlAndDocGeneration.test_wadl
lp.bugs.tests.test_bugchanges.TestBugChanges.test_change_information_type_using_api

Here's the failure information.

Error in test lp.bugs.tests.test_bugchanges.TestBugChanges.test_change_information_type_using_api
Traceback (most recent call last):
_StringException: librarian-log: {{{
2012-05-23 06:27:39+0530 [-] Log opened.
2012-05-23 06:27:39+0530 [-] twistd 11.1.0 (/usr/bin/python2.6 2.6.5) starting up.
2012-05-23 06:27:39+0530 [-] reactor class: twisted.internet.pollreactor.PollReactor.
2012-05-23 06:27:39+0530 [-] FileUploadFactory starting on 56734
2012-05-23 06:27:39+0530 [-] Starting factory <lp.services.librarianserver.libraryprotocol.FileUploadFactory instance at 0xa138d2c>
2012-05-23 06:27:39+0530 [-] Site starting on 54555
2012-05-23 06:27:39+0530 [-] Starting factory <twisted.web.server.Site instance at 0xa13860c>
2012-05-23 06:27:39+0530 [-] FileUploadFactory starting on 45123
2012-05-23 06:27:39+0530 [-] Starting factory <lp.services.librarianserver.libraryprotocol.FileUploadFactory instance at 0xa17604c>
2012-05-23 06:27:39+0530 [-] Site starting on 48076
2012-05-23 06:27:39+0530 [-] Starting factory <twisted.web.server.Site instance at 0xa17676c>
2012-05-23 06:27:39+0530 [-] Not using upstream librarian
2012-05-23 06:27:39+0530 [-] daemon ready!
}}}

Traceback (most recent call last):
  File "/home/gary/launchpad/lp/sandbox/lib/lp/bugs/tests/test_bugchanges.py", line 692, in test_change_information_type_using_api
    webservice = launchpadlib_for('test', person)
  File "/home/gary/launchpad/lp/sandbox/lib/lp/testing/_webservice.py", line 162, in launchpadlib_for
    version=version, cache=cache)
  File "/home/gary/launchpad/deps/eggs/launchpadlib-1.9.12-py2.6.egg/launchpadlib/launchpad.py", line 198, in __init__
    credentials, service_root, cache, timeout, proxy_info, version)
  File "/home/gary/launchpad/deps/eggs/lazr.restfulclient-0.12.2-py2.6.egg/lazr/restfulclient/resource.py", line 467, in __init__
    self._browser.get(root_resource), 'application/json')
  File "/home/gary/launchpad/deps/eggs/lazr.restfulclient-0.12.2-py2.6.egg/lazr/restfulclient/_browser.py", line 386, in get
    response, content = self._request(url, extra_headers=headers)
  File "/home/gary/launchpad/deps/eggs/lazr.restfulclient-0.12.2-py2.6.egg/lazr/restfulclient/_browser.py", line 337, in _request
    str(url), method=method, body=data, headers=headers)
  File "/home/gary/launchpad/deps/eggs/lazr.restfulclient-0.12.2-py2.6.egg/lazr/restfulclient/_browser.py", line 306, in _request_and_retry
    url, method=method, body=body, headers=headers)
  File "/home/gary/launchpad/deps/eggs/httplib2-0.6.0-py2.6.egg/httplib2/__init__.py", line 1129, in request
    (response, content) = self._request(conn, authority, uri, request_uri, method, body, headers, redirections, cachekey)
  File "/home/gary/launchpad/deps/eggs/launchpadlib-1.9.12-py2.6.egg/launchpadlib/launchpad.py", line 126, in _request
    LaunchpadOAuthAwareHttp, self)._request(*args)
  File "/home/gary/launchpad/deps/eggs/lazr.restfulclient-0.12.2-py2.6.egg/lazr/restfulclient/_browser.py", line 133, in _request
    redirections, cachekey)
  File "/home/gary/launchpad/deps/eggs/httplib2-0.6.0-py2.6.egg/httplib2/__init__.py", line 901, in _request
    (response, content) = self._conn_request(conn, request_uri, method, body, headers)
  File "/home/gary/launchpad/deps/eggs/httplib2-0.6.0-py2.6.egg/httplib2/__init__.py", line 871, in _conn_request
    response = conn.getresponse()
  File "/usr/lib/python2.6/httplib.py", line 984, in getresponse
    method=self._method)
  File "/usr/lib/python2.6/httplib.py", line 330, in __init__
    self.fp = sock.makefile('rb', 0)
AttributeError: 'NoneType' object has no attribute 'makefile'