title: Exports defaults else path not taken with Jest and ES6
body: <p>I'm having issues to pass my tests with 100% coverage. Istanbul say that <code>exports defaults Component</code> else path not taken.</p>
  
  <p>Because of that, I see in my generated html of istanbul that my tests are not completely at 100%. Mostly in the Statements and Branches tab.</p>
  
  <p>I'm using:</p>
  
  <ul>
  <li>React: 15.4.0 </li>
  <li>Jest: 17.0.2 </li>
  <li>Webpack: 1.12.11</li>
  </ul>
  
  <p>Any idea?</p>
  
  <p><a href="https://i.stack.imgur.com/CadHv.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/CadHv.png" alt="enter image description here"></a>
  <a href="https://i.stack.imgur.com/balKn.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/balKn.png" alt="enter image description here"></a></p>