Minecraft wiki entry for Development_versions, associated text: Fixed block placement issues with lighting.[15]
Game performance is now better from before.
Fixed Bottomless pit.
Jack o' Lantern emitting stronger light from the wrong face fixed.
Fixed the witch's texture being weird.
Partially fixed Nether lag by making the server do some of what used to be the client's work and increasing chunk load time slightly.[16]
Fixed some lighting bugs related to upside down slabs and stairs and farmland.