"undefined method `rewrite' for" aka @url considered harmful

{{133416492}} “link_to/url_for and related uses the ActionController::Base @url
instance variable to generate URLs, so if you (or plugins you’ve
installed) clobber it somehow, you’ll get this error.”
Thanks eden li via rails-talk. (for the Rails aware: I have a model named Url, so go figure how scaffolding named the instance variables in the associated controller :P )