The title says it all.
Sneaking should prevent you from falling off a block. In 1.4.3 it doesn't prevent you from falling off a chest. Might be related to the fixed hitbox of chests.
I have seen that enderchests have been updated too, so it might happen there too. Atm you can sneak on enderchests in 1.4.3, which contradicts the behaviour of normal chests
Also affects soul sand.
Linked issues
is duplicated by 28
relates to 2
Comments 45
This is also the (rather infamous) case with soul sand (the bug's as old as time itself), and with extended upward-facing pistons (extend while you have a block above your head to allow yourself to stand on the piston despite the head being in the way).
Confirmed for both chests and ender chests.
It only happens when the block below the chest has a hitbox that extends beyond the edge of the chest. The same thing happens with end portal frames when there is an open hatch on the block below them.