It was Richie Porte and Simon Clarke iircPlenty of rules. Fair play rules, no pre arranged deals and one that says you need to defend your OWN chances. Collusion is strictly forbidden. But it obviously can't be proven and you can always spin it like Ganna is defending his own chances in the end, even when we all know he's just there to help out his friend.
I think in the past 1 time the UCI actually punished for someone blatantly helping someone from another team, but it's a long time ago, and it was just some random time penalty that didn't matter anyways.