title: Select2 allowclear not working
body: <p>My select2 :</p>
  
  <pre><code>element.select2({
      allowClear: true,
      placeholder: 'blabla',
      data: {/*mydata*/}
  });
  </code></pre>
  
  <p>Problem is that, than select2 don't clear option's list when new data added (manually or via ajax request). </p>
  
  <p>On this, I decided to manualy clear options list, because select2 don't have same method to clear options list.</p>
  
  <pre><code>element.empty().trigger('change');
  </code></pre>
  
  <p>For showing new data I rebing the select2 to the same element.</p>
  
  <p>It's well work, but after that select2 set first item of data as selected option and allowClear with placeholder don't working. What would I not do, select2 after manualy clear items set first item to selected option.</p>
  
  <p>What I do wrong?</p>