I am unsure, but I beleive this is done by sentinal (Unsure).
It is a very good idea to have this enabled, plainly due to the fact, you can't ban any1 else, a genral ban is in place.
It's too early to be looking, but there should be some form of setting, that tells the script, what the maximum number of bans are. By increasing this by 1, the script will never think the list is full.