Merged r4414 from trunk.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/branches/1.0-stable@4415 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/models/issue.rb

@@ -237,7 +237,7 @@ class Issue < ActiveRecord::Base
       if !user.allowed_to?(:manage_subtasks, project)
         attrs.delete('parent_issue_id')
       elsif !attrs['parent_issue_id'].blank?
-        attrs.delete('parent_issue_id') unless Issue.visible(user).exists?(attrs['parent_issue_id'])
+        attrs.delete('parent_issue_id') unless Issue.visible(user).exists?(attrs['parent_issue_id'].to_i)
       end
     end