Comment 21 for bug 1415918

Indeed, these messages have to do with prep-bootdev not finding the PReP partition to wipe, but this should have been initialized by partman-prep -- the fact that it wasn't and that this bug isn't happening when the disks are wiped before doing the install still point to something being wrong in either how partman-prep sets up the prep partition (or fails to do so) or how prep-bootdev searches for the PReP partition. This is why I asked to see the output of parted (without realizing that it might not be available as such). As a next step should this need to be further investigated I would try to see whether clearing just one disk's partition 1 might let grub complete its installation. I suspect a stale prep partition from a previous install that can't be matched because it's not on the disk we pass as a parameter to prep-bootdev, so it can't be wiped, can't be used by grub-installer and grub so the resulting install may not be bootable.

Leaving this as Incomplete so it can be picked back up later should it be possible to reproduce it again (as per comment #10).