Tested using urllib3 1.20

```
>>> import urllib3
>>> http = urllib3.PoolManager()
>>> r = http.request('GET', 'https://online.chasecanada.ca/ChaseCanada_Consumer/Login.do')
>>> r.status
200
>>> r.headers
HTTPHeaderDict({'Date': 'Sat, 04 Feb 2017 20:09:21 GMT'})
>>>
```

I'm pretty sure the problem is caused by an invalid HTTP header returned by the server:

    HTTP/1.1 200 OK
    Date: Sat, 04 Feb 2017 19:16:34 GMT
    My Param: None
    [...]

It directly follows the Date response header, which is returned fine, but since no other response headers is returned, I think this broken header is breaking the HTTP response headers parser.

Of note: the `http.client.HTTPresponse.headers` object (`HTTPMessage`) shows all headers in `_payload`, but only the `Date` header in `_headers`.
Thus why I think this is a http.client issue, and not a urllib3 issue.