updater.sh: ensure that updater waits for lock and runs
Ensure that if already one instance of updater is running that we run another instance after it exits.
We need this for foris because that should ensure us that if it request updater's run that we really run it with latest updated configuration.
We might be able to somehow note that we want another updater's run and when updater.sh is exiting we should just check if we have that note and if so we should run updater in background again.