i had the same problem and all it took to fix was changing a line in /etc/apt/apt.conf back to the breezy default. ie. Acquire::http::Proxy "false"; to Acquire::::Proxy "false";
-- Incompatible with full URL HTTP requests from recent apt versions https://launchpad.net/bugs/46776 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
