wall-floor torch behavior with buds

When a torch was placed on the second block above a piston on the top of a block, the piston did not extend. However, when a torch placed in the same block was placed on the side of the block, the piston did extend. This seems odd as the torch should provide a redstone update to the piston regardless of which face of the block it is on.

This is not a bug about the whole thing about budding of pistons. This is simply about when the bud is supposed to happen.

To reproduce, simply place a piston down and THEN place a torch 2 blocks above it on a wall, as shown in the right side of the picture.

Then compare it to the building on the left side, starting with the piston and then the block with the torch on top.