How to reproduce

1. fetch a tree with nested set

   $root = Doctrine::getTable($model)->getTree()->findRoot($rootId);
   $treeObject= Doctrine::getTable($model)->getTree()->fetchTree($root->getId()); 
   

2. issue

   $root->getNode()->getChildren();
   
   or there will be a total query mess in a lambda function with a loop getChildren().
   ...
   <?php foreach($root->getChildren() as $child): ?>
      ....
   <?php endforeach; ?>
   ...
   
   

Problem is described more verbosely here – http://codeutopia.net/blog/2008/08/30/understanding-doctrines-nestedset-feature/

What behavior is expected

An already fetched record instance is returned, without calling database and without causing query flooding.

Like in propel.

In propel if you are calling ....::retrieveTree($id) it returns the root
with completed, pooled (cached) and linked tree.

What happens

An additional query is issued

This is a big slip in architecture of Doctrine`s nested set implementation.