Flaky test

[mbertrand]

This failed once when deploying a new RC release.

____________________ test_get_valid_edx_api_auth_unexpired _____________________

    @responses.activate
    @freeze_time("2019-03-24 11:50:36")
    def test_get_valid_edx_api_auth_unexpired():
        """Tests get_valid_edx_api_auth returns the current record if it is valid long enough"""
        auth = OpenEdxApiAuthFactory.create()
    
>       updated_auth = get_valid_edx_api_auth(auth.user)

courseware/api_test.py:251: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
courseware/api.py:358: in get_valid_edx_api_auth
    return _refresh_edx_api_auth(auth)
courseware/api.py:381: in _refresh_edx_api_auth
    client_secret=settings.OPENEDX_API_CLIENT_SECRET,
courseware/api.py:250: in _create_tokens_and_update_auth
    resp = requests.post(edx_url(OPENEDX_OAUTH2_ACCESS_TOKEN_PATH), data=params)
/opt/hostedtoolcache/Python/3.7.5/x64/lib/python3.7/site-packages/requests/api.py:117: in post
    return request('post', url, data=data, json=json, **kwargs)
/opt/hostedtoolcache/Python/3.7.5/x64/lib/python3.7/site-packages/requests/api.py:61: in request
    return session.request(method=method, url=url, **kwargs)
/opt/hostedtoolcache/Python/3.7.5/x64/lib/python3.7/site-packages/requests/sessions.py:529: in request
    resp = self.send(prep, **send_kwargs)
/opt/hostedtoolcache/Python/3.7.5/x64/lib/python3.7/site-packages/requests/sessions.py:645: in send
    r = adapter.send(request, **kwargs)
/opt/hostedtoolcache/Python/3.7.5/x64/lib/python3.7/site-packages/responses/__init__.py:841: in unbound_on_send
    return self._on_request(adapter, request, *a, **kwargs)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <responses.RequestsMock object at 0x7fca64b38c90>
adapter = <requests.adapters.HTTPAdapter object at 0x7fca4da0b1d0>
request = <PreparedRequest [POST]>
kwargs = {'cert': None, 'proxies': OrderedDict(), 'stream': False, 'timeout': None, ...}
match = None, match_failed_reasons = [], resp_callback = None
error_msg = "Connection refused by Responses - the call doesn't match any registered mock.\n\nRequest: \n- POST http://localhost:[180](https://github.com/mitodl/mitxpro/runs/5856049181?check_suite_focus=true#step:14:180)00/oauth2/access_token\n\nAvailable matches:\n"

    def _on_request(self, adapter, request, **kwargs):
        # add attributes params and req_kwargs to 'request' object for further match comparison
        # original request object does not have these attributes
        request.params = self._parse_request_params(request.path_url)
        request.req_kwargs = kwargs
    
        match, match_failed_reasons = self._find_match(request)
        resp_callback = self.response_callback
    
        if match is None:
            if any(
                [
                    p.match(request.url)
                    if isinstance(p, Pattern)
                    else request.url.startswith(p)
                    for p in self.passthru_prefixes
                ]
            ):
                logger.info("request.allowed-passthru", extra={"url": request.url})
                return _real_send(adapter, request, **kwargs)
    
            error_msg = (
                "Connection refused by Responses - the call doesn't "
                "match any registered mock.\n\n"
                "Request: \n"
                f"- {request.method} {request.url}\n\n"
                "Available matches:\n"
            )
            for i, m in enumerate(self.registered()):
                error_msg += "- {} {} {}\n".format(
                    m.method, m.url, match_failed_reasons[i]
                )
    
            if self.passthru_prefixes:
                error_msg += "Passthru prefixes:\n"
                for p in self.passthru_prefixes:
                    error_msg += "- {}\n".format(p)
    
            response = ConnectionError(error_msg)
            response.request = request
    
            self._calls.add(request, response)
>           raise response
E           requests.exceptions.ConnectionError: Connection refused by Responses - the call doesn't match any registered mock.
E           
E           Request: 
E           - POST http://localhost:18000/oauth2/access_token
E           
E           Available matches:

/opt/hostedtoolcache/Python/3.7.5/x64/lib/python3.7/site-packages/responses/__init__.py:815: ConnectionError