It hangs for me where a pre-created venv is present. When I hit ctrl-c it dumps a traceback which indicates it was stuck in some rpc connection retry attempt:

$ python run_tests.py openvswitch.test_ovs_tunnel
nose.config: INFO: Ignoring files matching ['^\\.', '^_', '^setup\\.py$']
TunnelTest
    testConstruct (openvswitch.test_ovs_tunnel.TunnelTest)      ^CTraceback (most recent call last):
  File "run_tests.py", line 67, in <module>
    main()
  File "run_tests.py", line 64, in main
    sys.exit(run_tests(c))
  File "/home/henry/Dev/openstack/quantum/quantum/common/test_lib.py", line 272, in run_tests
    return not core.run(config=c, testRunner=runner)
  File "/home/henry/Dev/openstack/quantum/.venv/local/lib/python2.7/site-packages/nose/core.py", line 284, in run
    return TestProgram(*arg, **kw).success
  File "/home/henry/Dev/openstack/quantum/.venv/local/lib/python2.7/site-packages/nose/core.py", line 118, in __init__
    **extra_args)
  File "/usr/lib/python2.7/unittest/main.py", line 95, in __init__
    self.runTests()
  File "/home/henry/Dev/openstack/quantum/.venv/local/lib/python2.7/site-packages/nose/core.py", line 197, in runTests
    result = self.testRunner.run(self.test)
  File "/home/henry/Dev/openstack/quantum/.venv/local/lib/python2.7/site-packages/nose/core.py", line 61, in run
    test(result)
  File "/home/henry/Dev/openstack/quantum/.venv/local/lib/python2.7/site-packages/nose/suite.py", line 176, in __call__
    return self.run(*arg, **kw)
  File "/home/henry/Dev/openstack/quantum/.venv/local/lib/python2.7/site-packages/nose/suite.py", line 223, in run
    test(orig)
  File "/home/henry/Dev/openstack/quantum/.venv/local/lib/python2.7/site-packages/nose/suite.py", line 176, in __call__
    return self.run(*arg, **kw)
  File "/home/henry/Dev/openstack/quantum/.venv/local/lib/python2.7/site-packages/nose/suite.py", line 223, in run
    test(orig)
  File "/home/henry/Dev/openstack/quantum/.venv/local/lib/python2.7/site-packages/nose/suite.py", line 176, in __call__
    return self.run(*arg, **kw)
  File "/home/henry/Dev/openstack/quantum/.venv/local/lib/python2.7/site-packages/nose/suite.py", line 223, in run
    test(orig)
  File "/home/henry/Dev/openstack/quantum/.venv/local/lib/python2.7/site-packages/nose/case.py", line 45, in __call__
    return self.run(*arg, **kwarg)
  File "/home/henry/Dev/openstack/quantum/.venv/local/lib/python2.7/site-packages/nose/case.py", line 133, in run
    self.runTest(result)
  File "/home/henry/Dev/openstack/quantum/.venv/local/lib/python2.7/site-packages/nose/case.py", line 151, in runTest
    test(result)
  File "/usr/lib/python2.7/unittest/case.py", line 391, in __call__
    return self.run(*args, **kwds)
  File "/usr/lib/python2.7/unittest/case.py", line 327, in run
    testMethod()
  File "/home/henry/Dev/openstack/quantum/quantum/tests/unit/openvswitch/test_ovs_tunnel.py", line 90, in testConstruct
    'sudo', 2, True)
  File "/home/henry/Dev/openstack/quantum/quantum/plugins/openvswitch/agent/ovs_quantum_agent.py", line 163, in __init__
    self.setup_rpc(integ_br)
  File "/home/henry/Dev/openstack/quantum/quantum/plugins/openvswitch/agent/ovs_quantum_agent.py", line 181, in setup_rpc
    consumers)
  File "/home/henry/Dev/openstack/quantum/quantum/agent/rpc.py", line 44, in create_consumers
    connection = rpc.create_connection(new=True)
  File "/home/henry/Dev/openstack/quantum/quantum/openstack/common/rpc/__init__.py", line 86, in create_connection
    return _get_impl().create_connection(cfg.CONF, new=new)
  File "/home/henry/Dev/openstack/quantum/quantum/openstack/common/rpc/impl_kombu.py", line 751, in create_connection
    rpc_amqp.get_connection_pool(conf, Connection))
  File "/home/henry/Dev/openstack/quantum/quantum/openstack/common/rpc/amqp.py", line 353, in create_connection
    return ConnectionContext(conf, connection_pool, pooled=not new)
  File "/home/henry/Dev/openstack/quantum/quantum/openstack/common/rpc/amqp.py", line 98, in __init__
    server_params=server_params)
  File "/home/henry/Dev/openstack/quantum/quantum/openstack/common/rpc/impl_kombu.py", line 438, in __init__
    self.reconnect()
  File "/home/henry/Dev/openstack/quantum/quantum/openstack/common/rpc/impl_kombu.py", line 549, in reconnect
    time.sleep(sleep_time)
KeyboardInterrupt