temporary pg .changed() fix: turn off returning for updates

lib/instance.js

@@ -475,7 +475,7 @@ module.exports = (function() {
     if (options.returning === undefined) {
     if (options.returning === undefined) {
       if (options.association) {
       if (options.association) {
         options.returning = false;
         options.returning = false;
-      } else {
+      } else if (this.isNewRecord) {
         options.returning = true;
         options.returning = true;
       }
       }
     }
     }