Fixed: "Loading..." icon does not disappear after adding a project member when...

Fixed: "Loading..." icon does not disappear after adding a project member when there is no other member to add (#7265).

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@4719 e93f8b46-1217-0410-a6f0-8f06a7374b81