# clean up dangling (running) children
for child in self.children:
if child.status == common.Status.RUNNING:
# this unfortunately knocks out it's running status for introspection
# but logically is the correct thing to do, see #132.
child.stop(common.Status.INVALID)
Composite.stop(self, new_status)
child.stop() method makes child as INVALID state
Composite.stop() method makes not INVALID behavior to INVALID behavior use child.stop() method again
https://github.com/splintered-reality/py_trees/blob/devel/py_trees/composites.py#L778
"behavior.terminate() called twice in Parallel's children when Parallel decorator is stopped" is known issue?