Modeling Algorithms - bopargcheck fails with extruded bezier

# draw session using provided script

Draw[1]> Draw[2]> source Attachment 1 (TXT)
Draw[3]> checkshape s0
This shape seems to be valid
Draw[4]> nbshapes s0
Number of shapes in s0
 VERTEX    : 4
 EDGE      : 8
 WIRE      : 5
 FACE      : 5
 SHELL     : 1
 SOLID     : 1
 COMPSOLID : 0
 COMPOUND  : 0
 SHAPE     : 24

Draw[5]> bopargcheck s0
Faulties, that can not be treated by BOP, are detected.

Draw[6]> bopargcheck s0 /I
Shape(s) seem(s) to be valid for BOP.