functional gate failed on assertion error

[hongbin]

Starting from a few days ago, the functional gate failed on test 'test_bay_create_and_delete'.

* Trace on client side (console.html):
2015-06-19 11:35:28.362 | 2015-06-19 11:35:28.352 | Traceback (most recent call last):
2015-06-19 11:35:28.363 | 2015-06-19 11:35:28.353 | File "magnum/tests/functional/test_magnum_python_client.py", line 200, in test_bay_create_and_delete
2015-06-19 11:35:28.365 | 2015-06-19 11:35:28.355 | "DELETE_COMPLETE"])
2015-06-19 11:35:28.367 | 2015-06-19 11:35:28.356 | File "magnum/tests/functional/test_magnum_python_client.py", line 82, in _wait_on_status
2015-06-19 11:35:28.368 | 2015-06-19 11:35:28.358 | status = cls.cs.bays.get(bay.uuid).status
2015-06-19 11:35:28.370 | 2015-06-19 11:35:28.360 | File "/opt/stack/new/python-magnumclient/magnumclient/v1/bays.py", line 82, in get
2015-06-19 11:35:28.372 | 2015-06-19 11:35:28.362 | return self._list(self._path(id))[0]
2015-06-19 11:35:28.373 | 2015-06-19 11:35:28.363 | File "/opt/stack/new/python-magnumclient/magnumclient/common/base.py", line 121, in _list
2015-06-19 11:35:28.375 | 2015-06-19 11:35:28.364 | resp, body = self.api.json_request('GET', url)
2015-06-19 11:35:28.376 | 2015-06-19 11:35:28.366 | File "/opt/stack/new/python-magnumclient/magnumclient/common/httpclient.py", line 196, in json_request
2015-06-19 11:35:28.377 | 2015-06-19 11:35:28.367 | resp, body_iter = self._http_request(url, method, **kwargs)
2015-06-19 11:35:28.379 | 2015-06-19 11:35:28.369 | File "/opt/stack/new/python-magnumclient/magnumclient/common/httpclient.py", line 179, in _http_request
2015-06-19 11:35:28.404 | 2015-06-19 11:35:28.394 | error_json.get('debuginfo'), method, url)
2015-06-19 11:35:28.405 | 2015-06-19 11:35:28.395 | magnumclient.openstack.common.apiclient.exceptions.InternalServerError: Internal Server Error (HTTP 500)

* Trace on server side (m-api):
Traceback (most recent call last):
  File "/usr/lib/python2.7/wsgiref/handlers.py", line 85, in run
    self.result = application(self.environ, self.start_response)
  File "/opt/stack/new/magnum/magnum/api/middleware/auth_token.py", line 58, in __call__
    return super(AuthTokenMiddleware, self).__call__(env, start_response)
  File "/usr/local/lib/python2.7/dist-packages/webob/dec.py", line 144, in __call__
    return resp(environ, start_response)
  File "/usr/local/lib/python2.7/dist-packages/webob/response.py", line 1021, in __call__
    start_response(self.status, headerlist)
  File "/usr/lib/python2.7/wsgiref/handlers.py", line 180, in start_response
    assert type(val) is StringType,"Header values must be strings"
AssertionError: Header values must be strings

* Note: It looks this error is not reproducible. So far, there is no report on successfully reproducing the error on development setup.