Stretch - Cron warning emails generated by backup2l

[andrewladlow]

When the cron script /etc/cron.daily/zz-backup2l runs, it generates the following warning message:

WARNING:

Volume is or was locked by another instance of 'backup2l'.

It appears that another instance of 'backup2l' is or was running concurrently.
This should not happen, but cannot be avoided completely with the present
implementation of locking in 'backup2l'. I am sorry!

The following steps should bring everything back into order:

1. Stop all instances of 'backup2l'.
2. Remove the lock file '/var/backups/localhost/all.lock' manually.
3. Re-run the backup.
4. Unmount the backup device (if desired).`

A new backup is created despite this warning message, but it could be a cause for concern.

[pcammish]

Fixed in upcoming merge

[andrewladlow]

Fixed with bc3fab4