Minecraft wiki entry for Development_versions, associated text: MC-134826 – Deleting a world doesn't remove it from the list until re-entering world list.
MC-134828 – Server crash - Ticking world entities.
MC-134833 – Fast movement.
MC-134858 – The TNT block state "explode" does not carry over to 1.13.1's "unstable".
MC-134905 – Exception ticking world.
MC-134919 – Crash when blowing up TNT in the Nether