Boat dismounts player in the ground

This is especially annoying when you play in a superflat world. I sat on a boat on a bedrock. Since it was a 2-block high gap, it put me a few millimeters below the block, and I glitched into the void (was playing survival. sad). This doesn't happen if there is at least 1-block room (i.e. 3 block high gap). You'll just be teleported on top of the boat instead of inside the block.

Probably caused by the same piece of code as MC-148869

Also happens with minecarts on rails when the room (specifically, the chosen exit tile) is 2 and a half blocks tall - if it's only 2 blocks tall, you take suffocation damage but land in the correct tile.