aircowboy- To the best of my knowledge its the real deal! I am just not to sure of the real story behind pic.
My best guess- I imagine that pic is staged e.g. the guy does this as a stunt regularly. Otherwise how would he know why engine stopped if not intentional??? why waste time climbing about outside when you should be setting up for an emergency landing? also check out the clear open land beneath for a reasonably safe landing if needed + Its a cub to balance airplane you need to sit in rear seat if flying solo! So this dude has balanced the Cub just for this stunt IMHO.

my 2c