task execution engine: fix addition of new tasks

dependencies of a task being added were filtered
  to remove already added ones all at once
however, as each new dependency is added, the
  'new' state of tasks could change
this fix checks and adds dependencies one at a time

tasks/Execute.scala

@@ -161,9 +161,11 @@ final class Execute[A[_] <: AnyRef](checkCycles: Boolean)(implicit view: NodeVie
 		else
 		{
 			forward(node) = IDSet(active)
-			val newD = active filter isNew
-			newD foreach { x => addNew(x) }
-			active foreach { addReverse(_, node) }
+			for(a <- active)
+			{
+				addChecked(a)
+				addReverse(a, node)
+			}
 		}
 
 		post {