BUGFIX: category name is reserved in multisite

app/models/topic.rb

@@ -55,7 +55,11 @@ class Topic < ActiveRecord::Base
                                         :case_sensitive => false,
                                         :collection => Proc.new{ Topic.listable_topics } }
 
-  validates :category_id, :presence => true ,:exclusion => {:in => [SiteSetting.uncategorized_category_id]},
+  validates :category_id,
+            :presence => true,
+            :exclusion => {
+              :in => Proc.new{[SiteSetting.uncategorized_category_id]}
+            },
             :if => Proc.new { |t|
                    (t.new_record? || t.category_id_changed?) &&
                    !SiteSetting.allow_uncategorized_topics &&