Windup 222 - Added the lost commit

This change was needed, because when XmlFile was used as nested condition in Iteration.over().when(XmlFile), it actually pushed some vertices into the varstack and when the perform() method of Iteration was called, on the top layer it had 2 different variables (one as result of intern when and one as the actual payload of Iteration). So now, when some internal condition is called, the result is just ignored (because we are interested only into true/false for one vertex) and new layer is created