unstoppable command block destroyer

While messing with command blocks I came up with a machine to eat chunks, It had many failed atempts, and two itterations, the first is on the other side of the huge hole, it would stop as soon as it got out of render distance, my second itteration was only menet to be more compact, but somehow ended up loading chunks and continuing once I closed and reopened the world, this was discovered in 14w28b
to start the schematic version, just break and replace the redstone block

a few wierd things I noticed, occasionaly flowing lava and water and cobblestone are left behind, and mineshafts seem to be immune to this