Affects Version/s: Snapshot 13w07a
Fix Version/s: None
Environment:Windows 7 Ultimate 64 bit
Java 7 Update 9 64-bit
It's very simple to reproduce this bug:
1- Place 3 or 4 layers of snow
2- Jump on it
3- Place another layer
Now you're inside the block.
I don't know what should happen when you place another layer, but falling inside the block is really weird.