+ def http_scheme(self):
+ """ Either "https:" or "https:", depending on the user's preferences """
+ return (
+ 'http:'
+ if self._downloader.params.get('prefer_insecure', False)
+ else 'https:')
+
+ def _proto_relative_url(self, url, scheme=None):
+ if url is None:
+ return url
+ if url.startswith('//'):
+ if scheme is None:
+ scheme = self.http_scheme()
+ return scheme + url
+ else:
+ return url
+