title: How do I get nested esi tags working?
body: <p>I am using ESI with Symfony and Varnish. 
  What I am trying to do is..</p>
  
  <p>Render an <code>esi</code> block, inside another <code>esi</code> block. </p>
  
  <p>Unfortunately the nested <code>esi</code> tags are not replaced.</p>
  
  <p>Any ideas why?</p>