empty root password

[Franck Royer]

Hi,

It's not a "how can I recover my root password" but something more weird.

I copied my root filesystem from a partition to another with rsync -Pia.
But since that moment, I don't need any password to log myself as root
or to do a "su" from a user who is in the wheel group.

I did some passwd on root, but that changes nothing. And my normal user
password wasn't affected.

What can I do ?

Thank you

Franck