(I file this here because I can't find a issue tracker on
openssh.org...)

I would like to make it possible to chroot users into their "group home"
instead of their own home. It's a rather specific requirement, but it
would be very useful in our case, where we want to allow multiple SFTP
chrooted users to access the same data, something that's currently very
hard to do.

The patch would be quite simple to do, but I am really rusty with C so
this shouldn't be merged in without proper testing and review.