"Inadvertently" probably means they didn't see it until the update was about to go live and it would have taken too long to fix itn OR they weren't sure what the problem was to begin with. In either case, they're going to see what it does to the game. If it leads to interesting builds and playstyles, they might leave in (with some tweaks). If it breaks the game, they'll track down the line of code and fix it. They are essentially saying that they fraked up, but they are keeping their eye on it.