Comment clarification. Appeasing Travis

lib/associations/has-many-double-linked.js

@@ -70,6 +70,7 @@ module.exports = (function() {
     })
 
     var unassociatedObjects = newAssociations.filter(function (obj) {
+      // Return only those associations that are new
       return !Utils._.find(oldAssociations, function (old) {
         return ((targetKeys.length === 1) ? obj[targetKeys[0]] === old[targetKeys[0]] : obj.id === old.id)
       })