Reported by Asger
Investigated by Freagarach.
rP23843 changed modifiers to explicitly support only string or numeric values. It turns out there was one case of a list being modified, build-territories.
This seems rather un-necessary since a string works rather well.
These long walls are the only case I can find of a replace tech with something non-string or non-numeric, so we ought to be in the clear.