It can't tell which backlot you were currently on when you did !nextmap and it assumes the first one.
111228 13:13:43 DEBUG 'Get cvar sv_mapRotation = ["sv_mapRotation" is: "gametype sab map mp_bloc gametype war map mp_broadcast gametype war map mp_crash gametype dom map mp_citystreets gametype sab map mp_carentan gametype war map mp_pipeline gametype dom map mp_bog gametype war map mp_backlot gametype war map mp_creek gametype sab map mp_strike gametype war map mp_convoy gametype dom map mp_crossfire gametype sab map mp_showdown gametype war map mp_countdown gametype sab map mp_crash gametype war map mp_strike gametype dom map mp_backlot gametype war map mp_vacant gametype war map mp_overgrown^7" default: "^7"\n Domain is any text]'