fix(ngOptions): use reference check only when not using trackBy

src/ng/directive/ngOptions.js

@@ -706,8 +706,7 @@ var ngOptionsDirective = ['$compile', '$parse', function($compile, $parse) {
         // Check to see if the value has changed due to the update to the options
         if (!ngModelCtrl.$isEmpty(previousValue)) {
           var nextValue = selectCtrl.readValue();
-          if (ngOptions.trackBy && !equals(previousValue, nextValue) ||
-                previousValue !== nextValue) {
+          if (ngOptions.trackBy ? !equals(previousValue, nextValue) : previousValue !== nextValue) {
             ngModelCtrl.$setViewValue(nextValue);
             ngModelCtrl.$render();
           }

test/ng/directive/ngOptionsSpec.js

@@ -1176,6 +1176,26 @@ describe('ngOptions', function() {
 
     });
 
+    it('should not set view value again if the tracked property of the model has not changed when using trackBy', function() {
+
+      createSelect({
+        'ng-model': 'selected',
+        'ng-options': 'item for item in arr track by item.id'
+      });
+
+      scope.$apply(function() {
+        scope.selected = {id: 10, label: 'ten'};
+      });
+
+      spyOn(element.controller('ngModel'), '$setViewValue');
+
+      scope.$apply(function() {
+        scope.arr[0] = {id: 10, label: 'ten'};
+      });
+
+      expect(element.controller('ngModel').$setViewValue).not.toHaveBeenCalled();
+    });
+
     it('should not re-render if a property of the model is changed when not using trackBy', function() {
 
       createSelect({