The #update_form action was only refreshing the issue attributes form,
so it's just a specialized JavaScript version of #new. This also removed
old code that was extracted in other places (@issue.new_statuses_allowed_to).
git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@4011 e93f8b46-1217-0410-a6f0-8f06a7374b81