Mobs in a boat and on fire do not cease being on fire when water is poured upon them

When a mob is in a boat and is on fire, it will not cease to be on fire when flowing water intersects the mob's hitbox. When not in a boat, a mob will cease to be on fire when flowing water intersects the mob's hitbox. This is an obvious inconsistency in the game's fire logic, and I suspect that it is a bug.