Marking 'high', because grub installation will fail later on if it doesn't find a prep partition (even though this is not required for P8 systems), so if you can't configure a prep partition this would break installs using manual partitioning.
Marking 'high', because grub installation will fail later on if it doesn't find a prep partition (even though this is not required for P8 systems), so if you can't configure a prep partition this would break installs using manual partitioning.