Shulkers in boats and minecarts do not sit up if previousely attached to blocks sideways

The bug

If a shulker is sideways onto a wall, and then put into the boat, it will still be sideways while in the boat.

How to reproduce

1. Build wall and use a shulker spawn egg onto the wall.
2. Build a platform under the shulker hanging onto the wall.
3. Place a boat and row it into the shulker, dismount the boat.
   → Shulker is put sideways into the boat