Stand on a partial block, like cake, slab, or chest. Run the command "/setblock ~ ~ ~ stone" The block above the one you are standing on will be set to stone. This only occurs if the block is thick enough, if run on a carpet for example, it will work correctly. Interestingly, if run on a 4-layer thick snow cover, it will work correctly, even though that is the same height as cake, which doesn't work correctly. This is because the player sinks 2 pixels into snow.

This bug only occurs when the command is directly run by the player, if you instead run "/execute @p ~ ~ ~ setblock ~ ~ ~ stone", it will work correctly.