don't trigger change event if noclobber: true

in the case where a refresh call returns, and there's un-persisted
changes on the model, we don't want to trigger a change event for those
properties.

pertains to #14

js/model.js

@@ -498,25 +498,29 @@ define([
         });
 
     Model.prototype._setOne = _.wrap(Model.prototype._setOne,
-        function(f, prop, newValue, currentValue, opts) {
+        function(f, prop, newValue, currentValue, opts, ctrl) {
             var i, l, args = Array.prototype.slice.call(arguments, 1),
                 inFlight = this._inFlight.save;
             if (opts.noclobber) {
                 if (this._changes[prop]) {
-                    return;
+                    ctrl.silent = true;
                 }
                 for (i = 0, l = inFlight.length; i < l; i++) {
                     if (inFlight[i].changes[prop]) {
-                        return;
+                        ctrl.silent = true;
                     }
                 }
+                if (ctrl.silent) {
+                    return;
+                }
             }
             if (opts.validate) {
                 var field = this._fieldFromPropName(prop);
                 try {
                     field.validate(newValue);
                 } catch (e) {
-                    return e;
+                    ctrl.error = e;
+                    return;
                 }
             }
             return f.apply(this, args);

js/tests/test_model_consistency.js

@@ -1124,5 +1124,18 @@ define([
         });
     });
 
+    asyncTest('setting changed value with noclobber doesnt trigger change', function() {
+        setup().then(function(c) {
+            var m = c.first(), changes = [];
+            m.on('change', function(eventName, changed) {
+                changes.push(changed);
+            });
+            m.set('required_field', 'foobar');
+            m.set('required_field', m.previous('required_field'), {noclobber: true});
+            equal(changes.length, 1);
+            start();
+        });
+    });
+
     start();
 });