Motivation:
If an exclusive dependency change stream B should be an exclusive dependency of stream A is requested and stream B is already a child of stream A...then we will add B to B's own children map and create a circular link in the priority tree. This leads to an infinite recursive loop and a stack overflow exception.
Modifications:
-when removeAllChildren is called it should not remove the exclusive dependency.
-unit test to ensure this case is covered.
Result:
No more circular link in the priority tree.