Fix #2044 - `once` events are properly removed after triggering

backbone.js

@@ -160,7 +160,7 @@
           if (callback || context) {
             for (j = 0, k = list.length; j < k; j++) {
               ev = list[j];
-              if ((callback && callback !== (ev.callback._callback || ev.callback)) ||
+              if ((callback && callback !== ev.callback._callback && callback !== ev.callback) ||
                   (context && context !== ev.context)) {
                 events.push(ev);
               }

test/events.js

@@ -364,4 +364,13 @@ $(document).ready(function() {
     _.extend({}, Backbone.Events).once('event').trigger('event');
   });
 
+  test("once removes event after running", 1, function() {
+    var obj = {};
+    _.extend(obj, Backbone.Events);
+    obj.once('event', function() {});
+    obj.trigger('event');
+    console.log(obj._events);
+    equal(obj._events['event'].length, 0, 'once should have removed bound event.');
+  });
+
 });