Added method to IM to remove objects by class and id. Then used it to…

… remove objects when updating counters.

activerecord/lib/active_record/counter_cache.rb

@@ -73,6 +73,8 @@ def update_counters(id, counters)
         "#{quoted_column} = COALESCE(#{quoted_column}, 0) #{operator} #{value.abs}"
       end
 
+      IdentityMap.remove_by_id(symbolized_base_class, id) if IdentityMap.enabled?
+
       update_all(updates.join(', '), primary_key => id )
     end
 

activerecord/lib/active_record/identity_map.rb

@@ -59,6 +59,10 @@ def remove(record)
         repository[record.class.symbolized_base_class].delete(record.id)
       end
 
+      def remove_by_id(symbolized_base_class, id)
+        repository[symbolized_base_class].delete(id)
+      end
+
       def clear
         repository.clear
       end