rman is clever

Well, sort of. Today, after patching one of my oracle database server against a migration issue that prevented it from shutting down clean. I finally managed to run the magic command:

alter database archivelog;

That would enable me to backup the database. Unfortunately, the disk space on this server is too low to allow two full backups of the database. I wanted to delete the old backup before doing the new one in rman but rman is too clever: You cannot delete the last remaining backup! I now have to find larger disks.