In pre2 the bug changed, the villager no longer gets teleported back to the start position. He glitches now out of the mincart und through blocks below, added attached imaged of that happening.
This can be reproduced (tested it twice), but the originial teleport bug seems to be gone in pre2.
This probably happend with the introduction of the Guardian. Hostile mobs now must be able to spawn inside water. So maybe the check for an Air-Block was simply removed and only the collision with objects remains.
if so, than it's sadly not a bug.