The HTTP status code constants in Python 3.5 http.client are not compatible with the constants in Python 3.4, since the str() behaviour is different. This breaks code: 

srittau@moby:~$ python3.5
Python 3.5.1+ (default, Jan 13 2016, 15:09:18) 
[GCC 5.3.1 20160101] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import http.client
>>> str(http.client.OK)
'HTTPStatus.OK'

vs:

rittau@moby:~$ python3.4
Python 3.4.4 (default, Jan  5 2016, 15:35:18) 
[GCC 5.3.1 20160101] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import http.client
>>> str(http.client.OK)
'200'