Minecraft wiki entry for Development_versions, associated text: MC-4973 – Zombie pigman from Nether portal still spawns even if doMobSpawning is false.
MC-10077 – Adjacent obsidian blocks prevent Nether portal appearing.
MC-28400 – Breeding animals gives xp even if doMobLoot gamerule is false.
MC-28768 – Horse breeding doesn't produce markings correctly on foal.
MC-29088 – Shearing sound does not play when shearing a mooshroom.
MC-30070 – Flowing lava can be blown up by TNT.