Comment 2 for bug 1067966

Something similar happens with the current version. The installation medium is automatically designated as /dev/sda and the target as /dev/sdb However, installing MBR fails, because it can only write that to /dev/sda, while /dev/sdb is the actual target.

See also https://askubuntu.com/questions/459620/unable-to-install-grub-in-dev-sda-when-installing-grub and https://askubuntu.com/questions/408617/ubuntu-minimal-cd-installs-grub-to-usb-drive

The installar should, upon failure, proactively as the user where to install it, instead of retrying only on the dev that just failed.