Minecraft wiki entry for Development_versions, associated text: Fixed a bug causing game launches to stall on Linux.
Fixed an error that would pop up when changing game directory in any configuration.
Fixed the launcher update progress bar not working on mac.
Fixed sounds not working in Minecraft versions prior to 1.6.
MCL-6280: No sound in older versions on native launcher, despite working in the Java launcher.
MCL-10486: minecraft-launcher 2.1.2339 hangs trying to load / run any version of minecraft.