The intention was to make sure the backup number always represents the same
backup. So in the successful case, the new backup is N+1 and the prior
deltas stored at N correctly represent that prior backup.
In the failure case and the prior backup deltas are empty, it removes the
empty delta. I als
When backups number N is initiated, it is initially labeled as
'active'. If interrupted, it is labeled as 'partial'.
Then when a backup is tried again, it is numbered 'N+1' and again
labeled as 'active'. This proceeds ad-infinitum until a successful
backup is completed.
The result can be large and