Delete interrupted backups on recovery
Delete interrupted backups on recovery

(cherry picked from commit d810c13fdff838fd443be2afa050f714cfb16625)

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