There shouldn't be stop signs at a round-about. The whole point of a round-about is to get rid of idling cars burning up gas and going no where. They are supposed to keep traffic rolling. I drove in Great Britain and once you get adjusted the round-abouts are nice. I just didn't like round-abouts that were four or five lanes wide, with about 6 different entrances/exits. Those were scary to me, although I'm sure if I'd grown up with them, it wouldn't be as scary.
Anyway, I think they should take out the stop signs. It completely defeats the purpose of having a round-about. Given that, as long as the stop signs are there, both cars and bicycles are supposed to stop, before proceeding. Too many bicyclists seem to be unaware that bicycles must follow the same rules as cars, in most states I know. My brother got pulled over by a cop in Davis, California when he was a teenager, because he slowed down at a stop sign, but did not come to a complete stop. Since we were new in town at the time, they let him off with a warning.
Regardless of all that, the people who rigged the trip line hopefully get caught and prosecuted for intent to commit bodily injury or something. It could have turned out very badly.