In Debian exists script: http://packages.debian.org/sid/molly-guard which - if reboot/shutdown is executed interactively - will ask you for hostname of machine which you think you are going to reboot/halt. Because sometimes it happens that you are rebooting different machine, than you think. Molly-guard provides wrapper for shutdown, reboot, halt and poweroff and put them in /sbin, which is executed before normal "shutdown", which reside in /usr/sbin, which is in $PATH later. Such hack is no more possible since migration to /usr/bin. It would be if you can provide some option in /etc/systemd/system.conf (which would be by default to off), which when enabled will mimic behaviour of molly-guard.
Debian supports diverting package contents, maybe that's a possible solution? I am not convinced that this is really something to support upstream in systemd.
Let's close this, I really don't think this should be in systemd uptsream. Sorry.
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