bug#55661: /etc/ssh/authorized_keys.d contains keys that have been removed

["Ludovic Courtès" <ludo@gnu.org>]

In the wake of <https://issues.guix.gnu.org/55359#3>, I realized that
/etc/ssh/authorized_keys.d is stateful: we copy files from the
authorized-key directory there, but files already present remain.
IOW, keys remain authorized.

Why are we copying that directory instead of making a symlink to the
directory computed by ‘authorized-key-directory’ that’s in /gnu/store?

This is explained in ‘openssh-activation’:

        ;; 'sshd' complains if the authorized-key directory and its parents
        ;; are group-writable, which rules out /gnu/store.  Thus we copy the
        ;; authorized-key directory to /etc.

Anyway, that code does intend remove the directory before copying it,
but there’s a typo:

  (delete-file-recursively "/etc/authorized_keys.d")

Can you spot it?

Ludo’.