[Linker] Linking d3dbsp related xassets from an existing fastfile fails to include d3dbsp string

[zombiedestroyer29]

On T6 when attempting to link a full combination of d3dbsp related xassets from an existing fastfile, like the following zone file, the linker fails to include the proper string of the relevant d3dbsp asset name in the resulting fastfile, causing it to be not found ingame.
gfxworld,maps/mp/mp_magma.d3dbsp
comworld,maps/mp/mp_magma.d3dbsp
gameworldmp,maps/mp/mp_magma.d3dbsp
mapents,maps/mp/mp_magma.d3dbsp
clipmap,maps/mp/mp_magma.d3dbsp

Here is the example of the string from mp_magma.ff itself