Simple relation hydratation not working properly

I'm not sure if i'm in the right place but i'm talking about this : https://github.com/doctrine/doctrine2

The following code trigger a lot more queries than it should and than it used to :

— code —

$qb = $em->createQueryBuilder()
->select('t, c, p')
->from('Task', 't')
->leftJoin('t.children', 'c')
->leftJoin('t.parent', 'p')
->orderBy('t.root, t.lft')
;

foreach( $qb->getQuery()->getResult() as $task)
{
$task->getChildren()->count();
}
— ---

edit: The code doesn't seems to be very nice in this editor, here is a pastbin version : http://pastebin.com/LCRfBCcV

With doctrine 2.1.2, only one query is needed.

Since doctrine 2.1.3, i almost have one query per loop iteration. It's the same with all next versions.

I'm using a NestedSet extension and Symfony 2.0.8, if i force doctrine version to 2.1.2 it works again with one query (with doctrine-common 2.1.4 and doctrine-dbal 2.1.5) so i think the problem is clearly introduced by doctrine itself (2.1.3).

I hope i was clear enough.