Comment 8 for bug 703009

Confirming for Ubuntu beta any my external usb drive (internal one disabled for testing)

# grub-install --debug --force /dev/sda
...
+ /usr/sbin/grub-probe --device-map=/boot/grub/device.map --target=device /boot/grub
/usr/sbin/grub-probe: error: cannot stat `aufs'.
+ grub_device=
+ exit 1