You use httplib for feed guesser but it don't handle HTTP/HTTPS proxies configured on system (with http_proxy variable for example). I admit it's a special situation.
There are two solutions, switch to requests library which automagically handle it, or handle it with os.environ and httplib2 internals Proxy support.
I think it could be better to use requests, it will allow use to reduce deps by one and by more homogeneous.
Edit: I just see that we don't use requests module. But I still prefer switch httplib2 by requests. 😄
Yeah, it is really special case. But if switching to requests will fix it without any extra work, that should be done. I do prefer requests api over httplib2, actually reason why I didn't pick requests was that my google-fu failed to find python3 support for it. It turns out that I do suck at googling.
I'll swap the libraries at some point today.
I agree that Python 3 support is not well specified.
You can see it in Feature support here.
Now fixed with requests.