Minecraft wiki entry for Development_versions, associated text: MC-169825 – "Multiplayer (3rd-party)" shows in the window title when disconnecting from a singleplayer world.
MC-169839 – Certain potion effects that override lower-level effects do not get removed after their duration ends.
MC-169840 – Drinking a level 1 potion under a level 2 beacon and leaving the area results in the effect being lost.
MC-169848 – Game crashes when trying to create a beehive from a planted tree.
MC-169886 – Warning icons for outdated singleplayer worlds do not appear.
MC-169930 – Simultaneously having 3 or more levels of the same potion effect only remembers one of the lower levels.