Light from previous blocks still there after clone/fill

If you have a volume you want to clone over that has a light source already in it, say torches, and the new clone area does not have a light source, then when you clone the not lit volume on to the lit volume, the blocks will still be lit up without the actual light source there. If you place a block where the light source was before the clone, the light from the block goes away, like it should.

I made it a video here: http://youtu.be/LzToDvBbQ9U