Fix: run() with a start_location now behaves properly.
Fix: run() with a start_location now behaves properly.

This means that if the current location when run() is called is empty ('')
the start_url is invoked. Otherwise, the location is not touched and the
current route is invoked.

cardil/sammy,cardil/sammy,Moykn/sammy,Moykn/sammy,Moykn/sammy,mtscout6/sammy,quirkey/sammy,mtscout6/sammy,cardil/sammy,quirkey/sammy