fix bad if

lib/associations/has-many.js

@@ -244,7 +244,7 @@ HasMany.prototype.injectGetter = function(obj) {
     return Model.all(options);
   };
 
-  if (!this.accessors.count) {
+  if (this.accessors.count) {
     obj[this.accessors.count] = function(options) {
       var model = association.target
         , sequelize = model.sequelize;