HTTPS: fix python2.3, persistent connections, don't explode if SSL is not available The urllib2 differences between python 2.3 and 2.4 are hidden by using keepalive.py, which also gives us support for persistent connections. Support for HTTPS is enabled only if there's a HTTPSHandler class in urllib2. It's not possible to have separate classes as handlers for HTTP and HTTPS: to support persistent HTTPS connections, we need a class that inherits from both keepalive.HTTPHandler and urllib2.HTTPSHandler. If we try to pass (an instance of) this class and (an instance of) the httphandler class to urllib2.build_opener, this function ends up getting confused, since both classes are subclasses of the HTTPHandler default handler, and raises an exception.