issue2550785: Using login from search (or logout) fails. when logging in from a search page or after a logout it fails with an error. The fix also keeps the user on the same page they started from (e.g. search results) before the login. There are two parts to this: 1) changes to the templates to properly define the __came_from form element. 2) code changes to the LoginAction code in roundup/cgi/actions.py. New test code added. Needed some additional functions from urllib so urllib_.py got a change.