delete status UNKNOWN

[gsmolk]

====================================================================================================================================================================
 Instance                    Version  ID      Recovery Time           Mode   WAL Mode  TLI       Time     Data     WAL  Zratio  Start LSN     Stop LSN      Status
====================================================================================================================================================================
 node  ----     QRN4X2  ----                           ARCHIVE   0/16      ----        0       0    1.00  0/0           0/0           UNKNOWN

$ pg_probackup delete -B /backup --instance node --status=unknown
ERROR: Unknown value for '--status' option: 'unknown'