Merged r9781 from trunk.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/branches/2.0-stable@9793 e93f8b46-1217-0410-a6f0-8f06a7374b81

lib/plugins/acts_as_list/lib/active_record/acts/list.rb

@@ -131,6 +131,15 @@ module ActiveRecord
           when 'lowest'
             move_to_bottom
           end
+          reset_positions_in_list
+        end
+
+        def reset_positions_in_list
+          acts_as_list_class.where(scope_condition).reorder("#{position_column} ASC, id ASC").each_with_index do |item, i|
+            unless item.send(position_column) == (i + 1)
+              acts_as_list_class.update_all({position_column => (i + 1)}, {:id => item.id})
+            end
+          end
         end
 
         # Removes the item from the list.
@@ -209,7 +218,7 @@ module ActiveRecord
           def bottom_item(except = nil)
             conditions = scope_condition
             conditions = "#{conditions} AND #{self.class.primary_key} != #{except.id}" if except
-            acts_as_list_class.find(:first, :conditions => conditions, :order => "#{position_column} DESC")
+            acts_as_list_class.where(conditions).reorder("#{position_column} DESC").first
           end
 
           # Forces item to assume the bottom position in the list.