title: React refs are not set up on tests if inside a react-bootstrap component
body: <p>I am using:</p>
  
  <ul>
  <li>"react": "0.13.3"</li>
  <li>"react-bootstrap": "0.26.4"</li>
  </ul>
  
  <p>Every time when I use a <code>ref</code> in a node inside a <code>&lt;Modal /&gt;</code> or other <a href="http://react-bootstrap.github.io/" rel="nofollow">React Bootstrap</a> component, they are correctly setted when I run the system normally, but at test environment they just disappear.</p>
  
  <p>I have tried all the render strategies of the react test utils, but seems to have no difference.</p>