Change the order of operations when using multiple backends for a location, and a forget/prune policy

[egdoc]

When performing a backup of a location to multiple backends, using a forget/prune policy, the order of operations is, basically:

1. Backup to backend1
2. Backup to backend2
3. Forget for backend1
4. Forget for backend2

With this strategy, if backup to backend1 fails, backup to backend2 is performed anyway, but if "forget" for backend1 fails, forget for backend2 is not performed, since process exists with error. Is it possible, somehow, to alternate backups and forget operations, so that the order is:

1. Backup to backend1
2. Forget to backend1
3. Backup to backend2
4. Forget to backend2

Or, eventually perform the second "forget" even if the first one fails?