1. place an infantry unit/ group and create a few move-waypoints, make sure the unit will face north when reaching them
2. create a trigger and synchronize it with a waypoint
3. start the mission and let the unit walk to the synchronized WP (if it's not the starting position already). Now wait a moment and the unit will start rotating about every second.
4. go back to the editor, select the whole set-up and turn it so the unit is facing south/ southwest now, and nothing should happen this time.