OLD_T_NEW Got a bad type code 20

GRASS GRASS user
1

I've checked dig_new_to_old_type() when v.in.dxf and dig_old_to_new_type() when
v.build.

dig_new_to_old_type never creates OLD TYPE 20.
however, dig_old_to_new_type complains OLD TYPE 20.

what's wrong?

i tested the following way:

  v.in.dxf dxf=21.dxf
  v.support map=21.2112