Minecraft wiki entry for Development_versions, associated text: MC-147264 – While riding certain entities, the player appears swimming.
MC-147266 – Intersecting solid blocks under certain circumstances causes the player to start crawling.
MC-147290 – In creative, it is not possible to use Sneak+Jump to place blocks adjacent to any block that is clickable.
MC-147356 – Crash while opening the Realms menu.
MC-147422 – Suffocating inside one block at feet.
MC-147456 – Spawners' delay tag is not being reset when at 0s.