Bug#994001: openssh-server: Almost locked out due #990456

On Thu, Sep 09, 2021 at 05:23:29PM +0100, Colin Watson wrote:
> We can add some kind of check that would fail the installation in this
> situation, but please migrate to using some other site-specific group
> for this ASAP.  The ssh/_ssh group is an internal implementation detail
> used only to ensure that private key material cannot be extracted from
> running ssh-agent processes using ptrace(2); it's not intended to have
> users added to it.

Done, thanks.