title: Select2 not opening after first selection on text field
body: <p>I'm using jquery select2 plugin to display a list of <code>&lt;li&gt;</code> items, but on an input text field instead of <code>&lt;select&gt;</code>. here is my html:</p>
  
  <pre><code>&lt;div class="item-holder"&gt;
      &lt;input type="hidden" name="item" id="item" value=""/&gt;
      &lt;input type="text" name="item_name" id="item_name" placeholder="Select Item" autocomplete="off"/&gt;
      &lt;ul class="item-list"&gt;
          &lt;ul class="item-list list"&gt;
              &lt;li&gt;item 1&lt;/li&gt;
              &lt;li&gt;item 2 &lt;/li&gt;
              &lt;li&gt;item 3 &lt;/li&gt;
              &lt;li&gt;item 4 &lt;/li&gt;                                
          &lt;/ul&gt;
      &lt;/ul&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>And my code is this:</p>
  
  <pre><code>$('#item_name').select2({ width: '185px', placeholder: "Select Item", allowClear : true});
  
  $("#item_name").on('click', function(e) {
      $(".item-list").toggle();
  });
  
  var options = {
      valueNames : [ 'item_name' ]
  };
  
  var brand_List = new List('item_holder', options);
  </code></pre>
  
  <p>Up to this stage everything works fine and smooth. When I select an item from the list, clear selection with keyboard, and want to select another option from the list, the list doesn't appear. seems like <code>select2</code> list doesn't appear for second time. Neither can I see 'clear' button if I enable <code>allowClear : true</code> option. Whats going wrong? </p>
  
  <p>Any help will be much appreciated. Thank you.</p>