Non destructive install is important.

[Phillip Susi]

Maybe instead of forcing a format, must mv / /old before installing? 
That way you won't have old files laying around in important places, but 
the user doesn't loose any data.

Colin Watson wrote:
> I made this change in 6.06.1 because 6.06 had a tendency to crash if you
> tried to install over an existing / without reformatting. I have no
> interest in supporting mutant systems where you don't reformat / before
> installing; it is very likely that attempting to do so will result in
> subtle latent bugs due to extra random files lying around from the
> previous installation that aren't handled by the package manager.
> 
> If you want to upgrade an existing installation, then you should use the
> normal package management tools to do so, not the installer. Therefore,
> the primary use case for installing over an existing system is moving
> from some other Linux distribution, and as above that is not supportable
> without reformatting /.
> 
> Cheers,
>