selftest hang in test_bzrdir.TestHTTPRedirections_readonly.test_loop

While testing the fix for bug 504102, I had selftest hang in test_bzrdir.TestHTTPRedirections_readonly.test_loop. I don't know if it's reproducible.

mbp@grace% strace -p 26937
Process 26937 attached - interrupt to quit
recvfrom(1023, ^C <unfinished ...>
Process 26937 detached

ved, entering debugger
** Type 'c' to continue or 'q' to stop the process
** Or SIGQUIT again to quit (and possibly dump core)
> /home/mbp/bzr/504102-test-isolation/bzrlib/breakin.py(41)_debug()
(Pdb) bt
  /tmp/testbzr-BOig6U.tmp/bzrlib.tests.test_bzrdir.TestHTTPRedirections_readonly.test_loop/work/bzr(142)<module>()
  /home/mbp/bzr/504102-test-isolation/bzrlib/commands.py(1105)main()
-> ret = run_bzr_catch_errors(argv)
  /home/mbp/bzr/504102-test-isolation/bzrlib/commands.py(1120)run_bzr_catch_errors()
-> return exception_to_return_code(run_bzr, argv)
  /home/mbp/bzr/504102-test-isolation/bzrlib/commands.py(826)exception_to_return_code()
-> return the_callable(*args, **kwargs)
  /home/mbp/bzr/504102-test-isolation/bzrlib/commands.py(1027)run_bzr()
-> ret = run(*run_argv)
  /home/mbp/bzr/504102-test-isolation/bzrlib/commands.py(638)run_argv_aliases()
-> return self.run(**all_cmd_args)
  /home/mbp/bzr/504102-test-isolation/bzrlib/builtins.py(3595)run()
-> result = selftest(**selftest_kwargs)
  /home/mbp/bzr/504102-test-isolation/bzrlib/tests/__init__.py(3396)selftest()
-> result_decorators=result_decorators,
  /home/mbp/bzr/504102-test-isolation/bzrlib/tests/__init__.py(2930)run_suite()
-> result = runner.run(suite)
  /home/mbp/bzr/504102-test-isolation/bzrlib/tests/__init__.py(636)run()
-> test.run(result)
  /home/mbp/bzr/504102-test-isolation/bzrlib/tests/__init__.py(3041)run()
-> return super(CountingDecorator, self).run(result)
  /home/mbp/bzr/504102-test-isolation/bzrlib/tests/__init__.py(3030)run()
-> test.run(result)
  /home/mbp/bzr/504102-test-isolation/bzrlib/tests/__init__.py(3030)run()
-> test.run(result)
  /home/mbp/bzr/504102-test-isolation/bzrlib/tests/TestUtil.py(84)run()
-> tests.pop().run(result)
  /home/mbp/lib/python/testtools/testcase.py(332)run()
-> return self.__RunTest(self, self.exception_handlers).run(result)
  /home/mbp/lib/python/testtools/runtest.py(63)run()
-> return self._run_one(actual_result)
  /home/mbp/lib/python/testtools/runtest.py(77)_run_one()
-> return self._run_prepared_result(ExtendedToOriginalDecorator(result))
  /home/mbp/lib/python/testtools/runtest.py(88)_run_prepared_result()
-> self._run_core()
  /home/mbp/lib/python/testtools/runtest.py(105)_run_core()
-> self.case._run_test_method, self.result):
  /home/mbp/lib/python/testtools/runtest.py(128)_run_user()
-> return fn(*args)
  /home/mbp/lib/python/testtools/testcase.py(369)_run_test_method()
-> testMethod()
  /home/mbp/bzr/504102-test-isolation/bzrlib/tests/test_bzrdir.py(1135)test_loop()
-> bzrdir.BzrDir.open_from_transport, newt)
  /home/mbp/bzr/504102-test-isolation/bzrlib/tests/__init__.py(1240)assertRaises()
-> callableObj(*args, **kwargs)
  /home/mbp/bzr/504102-test-isolation/bzrlib/bzrdir.py(873)open_from_transport()
-> redirected)
  /home/mbp/bzr/504102-test-isolation/bzrlib/transport/__init__.py(1644)do_catching_redirections()
-> return action(transport)
  /home/mbp/bzr/504102-test-isolation/bzrlib/bzrdir.py(860)find_format()
-> transport, _server_formats=_server_formats)
  /home/mbp/bzr/504102-test-isolation/bzrlib/bzrdir.py(1820)find_format()
-> return format.probe_transport(transport)
  /home/mbp/bzr/504102-test-isolation/bzrlib/bzrdir.py(1830)probe_transport()
-> format_string = transport.get_bytes(".bzr/branch-format")
  /home/mbp/bzr/504102-test-isolation/bzrlib/transport/__init__.py(609)get_bytes()
-> f = self.get(relpath)
  /home/mbp/bzr/504102-test-isolation/bzrlib/transport/decorator.py(103)get()
  /home/mbp/bzr/504102-test-isolation/bzrlib/transport/http/__init__.py(126)get()
-> code, response_file = self._get(relpath, None)
  /home/mbp/bzr/504102-test-isolation/bzrlib/transport/http/_urllib.py(118)_get()
  /home/mbp/bzr/504102-test-isolation/bzrlib/transport/http/_urllib.py(79)_perform()
  /usr/lib/python2.6/urllib2.py(389)open()
  /usr/lib/python2.6/urllib2.py(407)_open()
  /usr/lib/python2.6/urllib2.py(367)_call_chain()
  /home/mbp/bzr/504102-test-isolation/bzrlib/transport/http/_urllib2_wrappers.py(684)http_open()
  /home/mbp/bzr/504102-test-isolation/bzrlib/transport/http/_urllib2_wrappers.py(624)do_open()
  /home/mbp/bzr/504102-test-isolation/bzrlib/transport/http/_urllib2_wrappers.py(243)getresponse()
  /usr/lib/python2.6/httplib.py(974)getresponse()
  /home/mbp/bzr/504102-test-isolation/bzrlib/transport/http/_urllib2_wrappers.py(164)begin()
  /usr/lib/python2.6/httplib.py(391)begin()
  /usr/lib/python2.6/httplib.py(349)_read_status()
  /home/mbp/bzr/504102-test-isolation/bzrlib/transport/http/_urllib2_wrappers.py(99)readline()
  /usr/lib/python2.6/socket.py(406)readline()
> /home/mbp/bzr/504102-test-isolation/bzrlib/breakin.py(41)_debug()