Overwrites for mapgen made to allow special vehicle spawns, which as you can tell borks quests that reference them.
The reason for these is, well…normally if you have multiple mapgen files of the same name, it will pick one at random instead of allowing overwriting.
Wait…I COULD use the weight entry to make the modded version massively more likely to be picked. This would be awkward for multi-map-tile items, like the bandit camp. Less hassle to just dummy it out, as forklifts are the only vehicles TOTALLY depend on mapgen to exist.