Bad html tree rendering

Hi,

on the site map page when it render a taxonomy tree, the HTML looks like:

<ul>
  <li>...</li>
  <ul>
    <li>...</li>
  </ul>
  <li>...</li>
</ul>

But it's not the good way to render a tree, it result on a html syntax warning and a flat tree.

The HTML should be:

<ul>
  <li>...
    <ul>
      <li>...</li>
    </ul>
  </li>
  <li>...</li>
</ul>