When i ride pig from full block up on half slab, pig jumps in front of the slab, like if it was a full block. Ride on half slabs and going from slab up to full block works fine, without jumping.
Also pig not controlled by player will get up on half slab just fine, he jumps to get on slab only, when player is riding on him.

Pig should get up on slab without jumping or slowing down, like a player.
Pig will jump to get on the slab, even when it's not necessary.