s->nr = segment_count++;
#ifdef CHECKS
+ /* notice: on some systems (with some compilers), for the line
+ (1073741823,-1073741824)->(1073741823,1073741823)
+ we get LINE_EQ(s->a, s) == 1.
+ That's why we now clamp to 26 bit.
+ */
assert(LINE_EQ(s->a, s) == 0);
assert(LINE_EQ(s->b, s) == 0);