Steps to Reproduce

1. Make a Nether Portal in Overworld.
2. Enter the portal.
3. Move exit portal in Nether to a SE chunk border (X+Z+) like attachment C. (Bug more noticeable if portal is placed mid-air.)
4. Then make a wall of solid blocks covering the portal on the north and west sides (-Z and -X) of the exit portal. (Bug is more noticeable. If you do not place a floor below the wall other than the portal frame.)
5. Go back and forth through portal until you end up clipping through wall upon exit.

Expected result
Player ends up within the portal frame of the exit portal in the Nether since the west and north are blocked.

Observed result
Player sometimes ends up in wall and due to player physics, clips out the other side. Without a floor, the player would fall into lava like attachments A and B. Not a nice way to die.