Here is the rule: "An element in a city, fort or camp or in bad going (other than marsh or gully) or whose pursuit move would cross a battlefield edge or enter such bad going, does not pursue."
I have read this to mean that the element "does not pursue." That is to say, it does not start to pursue. Otherwise the rule would read the element pursues until it reaches the various things. I guess the pursuing element is somehow ESP, knowing that behind It's opponent there were some bad stuff.
Not consistant in reality as pursuing people stop immediately as they could encounted an obstacle farther but we will apply the rule, hope it will be corrected in 3.1. Thank you very much for your reply.