The edje_part_recalc calculates next postion(p3).
Please refer to following line.
p3->final.y = INTP(p1->final.y, p2->final.y, pos);
If the condition is as blow, then p3->final.y becomes -50 only if pos is 1.0.
Because INP uses TO_INT not TO_INT_ROUND.
p1->final.y == -32 p2->final.y == -50
So we had nonsmooth ending of transition.