title: Odoo 10 - Qweb t-if t-else syntax
body: <p>I do not know which is the right syntax for if-else in qweb.</p>
  
  <pre class="lang-xml prettyprint-override"><code>&lt;t t-if="origin != l.origin"&gt;
    &lt;td&gt;foo&lt;/td&gt;
  &lt;t t-else/&gt;
    &lt;td&gt;bar&lt;/td&gt;
  &lt;/t&gt;
  </code></pre>
  
  <p>What is wrong here?</p>