It would seem this shuffle guarantees that no element remains in it's current position. This seems less than random.

My tests show that SOME elements stay in place !
Did I miss something ?

Note: I suspect however that the distribution is not perfect(the items "don't move too far from their position" so i suspect the "distribution" to be biased)...

Anyway it's ok for me the way it is, just have to remember it's not a true 'statistical random' change...