title: backbone.js model.set is not working
body: <p>I'm trying to use backbone.js model.set property.  The second alert function should fire off after todo1.set is being implemented.  However it is not.<br>
  Here is the jsfiddle link: <strong><a href="http://jsfiddle.net/SGEkn/" rel="noreferrer">http://jsfiddle.net/SGEkn/</a></strong> </p>
  
  <pre><code>var Todo = Backbone.Model.extend({
          defaults: {
              title: "Harsh",
              completed: false
          }, 
          initialize: function() {
              console.log('This model has been initialized.')
          }
      });
  
  var todo2 = new Todo({
      title: 'Set through instantiation.',
      completed: true
  });
  console.log('Todo title: ' + todo2.get('title'));
  console.log('Todo completed ' + todo2.get('completed'));
  
  alert("ok");
  
  todo2.set("title", 'Title set');
  
  alert("ok");
  
  console.log(todo2.get('title'));
  todo.set("completed", false);
  
  console.log('completed: ' + todo2.get('completed'));
  </code></pre>