as this is my first time submitting a bug report I apologize if I am doing anything wrong here, but recently I was building an automatic sugarcane harvester powered by pistons, empty, it works fine, but the second I grow sugarcane in it and press the button to harvest, the piston fires and cuts down the sugarcane, but in retracting, the top piston leaves behind a visible ghost that I actually have to go up to and delete in order for the sugarcane to continue growing, the piston will still work regardless of this ghost but it reduces the machine to 1/2 efficiency, I would assume this is a glitch of some sort, you might notice from the screenshot that I have magic launcher (to allow me to allocate more ram to the game) along with a 512x512 vanilla texture pack, realistic water and shaders, I don't think this would adversely effect the pistons though and other than this, I have no mods on this jar file besides the above stated (and optfine but i thought that was for graphics and such)

i really don't have any idea what would be causing this but you should be able to see that this is clearly not how it's suppose to work.