vaendryl/Sunrider — pull request #101 by DoumanAsh (2014-10-08 05:14:35+00:00)
Title: Prevent movement toward None

best_hex = None originally.
Since current_location is always non-None next check will lead to strange result:
>if old_spot == best_hex:

Ship will try to move toward None and so it will do nothing at all.