When quest locations, goody huts, and hero encampments are on top of a road they all cause units following the road to path off through the wilderness rather than go through that location (even though they can't use it if there is no hero in the army). See the arrows pathing off and back on the road in the picture. That's the path my spearmen chose to follow on their own in the middle of a larger trip (in other words their destination was not the space they're standing in).
Is this intended or a bug?
