Shulkers teleport out of boats/minecarts when duplicating

If a shulker in a minecart gets hit by a shulker bullet and multiplies, the new shulker gets placed at the feet position of the originial instead of in the minecart, which causes them both to teleport out of the minecart.

Expected results: The new shulker ends up in the same minecart the old one was in, and the old one teleports away

Actual results: The new shulker ends up on the block under the minecart or inside the rail, and they both teleport away.

(all of this happens the same with boats instead of minecarts too)