title: $getJSON .fail not firing
body: <p>Can't alert $getJSON .fail:</p>
  
  <pre><code>this.flickrPics = ko.observableArray();
  ko.computed(function() {
  
      $.getJSON(
          'https://api.flickr.com/services/feeds/photos_public.gne?jsoncallback=?',
          {
              tags : data.name,
              format : 'json'
          })
      .done(function(response) {
              for (var i = 0; i &lt; 10; i++) {
                  self.flickrPics.push(response.items[i].media.m);
              }
      })
      .fail(function(error) {
          alert(error + 'error');
          // $('.pics-box h2').text("sorry, pictures cant be loaded at the moment");
      });
  
  }, this);
  </code></pre>
  
  <p>Everything works perfect except for .fail. If i mess up with url, nothing happens, only get console errors of failed ajax calls. What am I doing wrong?</p>