When exiting a minecart/boat the game checks if there is a block either one or two blocks below a tested location. However in negative coordinates this check tests the blocks next to the desired location.
So when trying to place the player at the coordinate -10/60/10 the game checks -9/59/10 and -9/58/10 for solid blocks instead of -10/(59/58)/10.
This doesn't happen with positive coordinates.

Steps to Reproduce:
1. place minecart on a pillar (at least two blocks high) in a location with either a negative x or z coordinate. (eg -10/60/10)
2. exit the minecart
3. observe that you where placed next to the minecart in the air.