From Minecraft Wiki
April 20, 2011
Beta 1.5_01 was released to fix some of the bugs and crashes in Beta 1.5.
8 bugs fixed
- Blocks can now be placed on snow.
- Rain no longer goes through translucent blocks.
- Pumpkin and Jack o'Lantern inventory texture now correctly faces forward.
- Pumpkins are no longer worn backward on the player.
- Game no longer crashes when rails are placed next to detector rails, or vice versa.
- Wolves are less common than in 1.5, but still more common than in 1.4.
- Blocks cannot be placed back into the output slot of furnaces, thus fixing the statistic exploit.
- If Minecraft detects a broken save file, it will attempt to recover the world.