systemd/system/sshkeys: Make execution more robust

The service failed when the unit to start was masked. Since it involves
networking, the service can fail and if it does we should restart.
Prevent execution when it has no chance to succeed because the unit to
start is masked but in all other cases try to restart on failure.

systemd/system/sshkeys.service

@@ -22,6 +22,8 @@ ConditionKernelCommandLine=|coreos.oem.id=openstack
 [Service]
 Type=oneshot
 RemainAfterExit=yes
+Restart=on-failure
+ExecCondition=/usr/bin/bash -c 'if [ $("readlink -f /etc/systemd/system/[email protected]") = "/dev/null" ]; then exit 1; fi'
 ExecStart=/usr/bin/systemctl start [email protected]
 
 [Install]