Only show status as ok if there is at least one backup
Only show status as ok if there is at least one backup

(cherry picked from commit f3e8daf59a7b2d7998d36bbe2e095953ba55089d)

uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend