HTTPHeaderDict incompatible with python-requests' CaseInsensitiveDict

[atodorov]

Hi, please see details here, especially comments #2 and #3 on that bug:
https://bugzilla.redhat.com/show_bug.cgi?id=1241561

On line 93 of requests/adapters.py there is:

response.headers = CaseInsensitiveDict(getattr(resp, 'headers', {}))

where resp['headers'] is now of type urllib3.HTTPHeaderDict so the following happens before and after this line is executed:

resp['headers'] is

HTTPHeaderDict({'soapserver': 'SOAP::Lite/Perl/1.11', 'x-xss-protection': '1; mode=block', 'x-content-type-options': 'nosniff', 'content-encoding': 'gzip', 'transfer-encoding': 'chunked', 'set-cookie': 'Bugzilla_login_request_cookie=or9UbA03it; domain=bugzilla.redhat.com; path=/; HttpOnly', 'vary': 'Accept-Encoding,User-Agent', 'server': 'Apache', 'connection': 'close', 'date': 'Thu, 09 Jul 2015 15:33:28 GMT', 'x-frame-options': 'SAMEORIGIN', 'content-type': 'text/xml'})

response.headers is 

<class 'requests.structures.CaseInsensitiveDict'> {'soapserver': ('soapserver', 'SOAP::Lite/Perl/1.11'), 'x-xss-protection': ('x-xss-protection', '1; mode=block'), 'x-content-type-options': ('x-content-type-options', 'nosniff'), 'content-encoding': ('content-encoding', 'gzip'), 'transfer-encoding': ('transfer-encoding', 'chunked'), 'set-cookie': ('set-cookie', 'Bugzilla_login_request_cookie=or9UbA03it; domain=bugzilla.redhat.com; path=/; HttpOnly'), 'vary': ('vary', 'Accept-Encoding,User-Agent'), 'server': ('server', 'Apache'), 'connection': ('connection', 'close'), 'date': ('date', 'Thu, 09 Jul 2015 15:33:28 GMT'), 'x-frame-options': ('x-frame-options', 'SAMEORIGIN'), 'content-type': ('content-type', 'text/xml')}

then the value for content-type becomes ('content-type', 'text/xml') which breaks elsewhere.

We can either patch python-request to account for that (I've found one place and it works for me) or better provide a backward compatible update to urllib3. Any idea if we can make the later ?

[shazow]

I believe this is effectively a dupe of #633, please correct me if I'm mistaken.