title: Datepicker returning uncaught typeError: undefined 'currentDay'
body: <p>I've been using jQuery UI with Bootstrap and I seem to run into a problem that I haven't had before. I'm not sure what has changed; I've tried setting back different version of jQuery and I didn't update the jQuery UI in the meanwhile. So I'm not exactly sure what broke.</p>
  
  <p>The error from the console when I click on any date in the datepicker returns:</p>
  
  <pre><code>Uncaught TypeError: Cannot set property 'currentDay' of undefined 
  </code></pre>
  
  <p>The code is fairly straightforward as one would expect from a datepicker:</p>
  
  <pre><code>$(".datepicker").datepicker({
  dateFormat: 'dd-mm-yy'
  }); 
  </code></pre>
  
  <p>With the following HTML:</p>
  
  <pre><code>&lt;input type="text" class="datepicker" /&gt;
  </code></pre>
  
  <p>Is this a bug that should be reported (since no other Google matches turn up) or is it something else I've missed?</p>