Curves behaved totally bad suddenly. Caused by Campbell code cleanup, replacing
this:
/* this is for float inaccuracy */
if (t < knots[0])
t = knots[0];
else if (t > knots[opp2])
t = knots[opp2];
with:
t = (t < knots[0]) ? knots[0] : knots[opp2];
Tss!