Current rear GitHub master
with latest Git commit 01f3515
(i.e. with #944 fixed)
on SLES12-SP2-beta5.

In the recovery system after successful "rear recover"
"reboot" does not work:

RESCUE g62:~ # rear -d -D recover
...
Finished recovering your system. You can explore it under '/mnt/local'.

RESCUE g62:~ # reboot
Failed to start reboot.target: Transaction contains conflicting jobs 'stop' and 'start' for reboot.service. Probably contradicting requirement dependencies configured.
Failed to talk to init daemon.

Easy workaround:

RESCUE g62:~ # umount -a
umount: /sys/fs/cgroup/systemd: target is busy
        (In some cases useful info about processes that
         use the device is found by lsof(8) or fuser(1).)
umount: /sys/fs/cgroup: target is busy
        (In some cases useful info about processes that
         use the device is found by lsof(8) or fuser(1).)
umount: /run: target is busy
        (In some cases useful info about processes that
         use the device is found by lsof(8) or fuser(1).)
umount: /dev: target is busy
        (In some cases useful info about processes that
         use the device is found by lsof(8) or fuser(1).)
umount: /: not mounted

RESCUE g62:~ # reboot -f
Rebooting.

I guess something related to systemd needs to be enhanced
in the rear recovery system to match newest fancy systemd stuff.

Because there is an easy workaround there is no time pressure
to get this done for Rear version 1.19 and therefore I set
the milestone to "Rear future".