Turning on debug output for python 3 urllib

You were right the first time. You can simply add the line http.client.HTTPConnection.debuglevel = 1 at the start of your file to turn on HTTP debugging application-wide. urllib.request still uses http.client.

It seems that there's also a way to set the debuglevel for a single handler (by creating urllib.request.HTTPHandler(debuglevel=1) and building an opener with that), but on my installation of Python3 (3.0b3) it's not actually implemented. I imagine that's changed in more recent versions!