As much of a "bug" as that seems, are there any saves that depend on it? I think the way the developers do it is they don't want even one save to be broken by any changes they make. Thus bug fixes are few and far between as often a person will implement a game glitch (possibly mistaking it for an intentional feature of the game) in order to make their save work.
Actually, all that needs to be done with the saves that currently rely on clone to break is a simple thing that can be fixed in 2 seconds. It wouldn't break very many saves in the first place and it would make original clone truly indestructible. We already have 2 destructible versions of clone, so why not make regular clone completely indestructible?