Potential extra waypoints in follow_new_path() when plan contains a docking waypoint

[Yadunund]

As reported here #272 (comment)

When a plan contains an entry dock event, it appears that the adapter may be including the lane entry vertex twice along with the dock waypoint itself in the list of waypoints passed to follow_new_path(). The expectation would be for the list of waypoints to only contain waypoints up to the entry vertex.