My boat crashed and broke in MC version 1.12.2 even though the boat crashing is supposed to have been removed in the 1.9 update.

I was in the nether transporting some villagers to my base. There is a staircase (no stair blocks) that travels down from the level of the villager portal to the level of my base portal. When I had a priest in the boat with me, I held down the forward key, hitting (I think) the base which is not flat, but has an upward stair that would prevent the villagers from going back up the tunnel. I've been going down this stair with 12 other villagers before this with no issue, with always the same movements: Forward, bounce off two steps and fall diagonally into the small pit. Also, to be clear, when I was in water and ran into blocks, the boats did not crash into wood and sticks.

I am a bit confused as to how this happened, but I'm not really concerned the implications.

Also attached are some screenshots if anyone wants to try to recreate the bug.