Artist David Bugnon wanted to paint/Photoshop/draw a tribute to conservative muckraker Andrew Breitbart and didn't intend to sell what was discovered to be a near-copy of Assassin's Creed artwork. But it went on sale nonetheless. He's yanked it and apologized.
Completely re-tracing a drawing with a different pen doesn't make it original. Yes photo-chopping is a technique used by professional matte painters.
And the idea is to modify the new chopped portions, often upwards of tens or hundreds of chopped portions, enough so that they are unrecognizable from the original and then combining them to create an image even further and less related to the original. That's not what happened here. This is tracing with a different type of drawing utensil using 2 copyrighted images, both of which look incredibly similar to the original.