The 15w40a snapshot for 1.9 has been released on September 30, 2015, and has a few changes:
- Certain changes to mob pathfinding, including avoiding fire and cacti, and running towards nearby water when lit on fire. (Blazes do not avoid fire, obviously)
- Shulkers no longer attack players in Peaceful.
- Shulker bullets no longer spawn in Peaceful.
- Health regenerates faster when saturation is full.
- Regenerating health increases exhaustion by 4 points rather than 3.
- And of course, multiple bug fixes and optimizations.
Edit: The next snapshot version, 15w40b, fixes the bug that didn’t let players join servers.