There seems to be some problems with the UVs, only one frame is exported,
and various model params don't get set (eye position, size, bounding
radius, synctype, flags), but the size and shape look right in qf :).
Except for the normal index in the frame bounds (and potentially frame
names with junk after the terminating nul), the output is identical to the
input for:
mdl=MDL().read("invisibl.mdl")
mdl.write("test.mdl")