Wrong result obtained by intersection algorithm.

# Use the following DRAW commands to reproduce the problem:
#---------------------
# 1.
restore b1_008_1 b1
restore b2_008_1 b2
mksurface s1 b1
mksurface s2 b2

# problem: incomplete intersection
intersect i s1 s2

# problem: incomplete intersection
bopcurves b1 b2
#---------------------
# 2
restore b1_008_2 b1
restore b2_008_2 b2
mksurface s1 b1
mksurface s2 b2

# problem: not splitted intersection curves
intersect i s1 s2

# problem: not splitted intersection curves
bopcurves b1 b2