Many fetches include a call to eZContentObjectTreeNode:getLimitationList(), even when passing in an empty limitation array.

Normally, no problem, but all SSO Handler calls can be initiated by eZUser::current(), which is called immediately in getLimitationList(). If any SSO Handler function makes a call to a fetch, using getLimitationList(), an infinite loop is created. In my tests, this crashes the apache worker process.

A fix would enable calling eZContentObjectTreeNode::subTreeByNodeID() or similar functions from the SSO handler classes, without creating an infinite loop in php.

Note, I've provided a patch in github fork: https://github.com/ezsystems/ezpublish/pull/541