Fixed: watchers selection lost when issue creation fails (#5406). #watched_by? was fixed in order to work with #watcher_user_ids= used in controllers on unsaved objects.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@3705 e93f8b46-1217-0410-a6f0-8f06a7374b81