Bug#187135: grub-installer: Fail if /boot/ is separate partition

[Petter Reinholdtsen <pere@hungry.com>]

Package: grub-installer
Version: 0.0.7
Severity: important

When trying to install grub using grub-installer on a hard drive with
the following partitioning, it fails.

  /dev/sda1 /     ext2
  /dev/sda6 /boot ext2
  /dev/sda7 /home ext2

This is the error message from grub-installer:

  Could not find device for /boot: Not found or not a block device.
  grub-installer: error: Running 'grub-installer "(hd0)"' failed.
  grub-installer's postinst exited with status 256

The content of /target/etc/fstab looks sane, so I think grub-installer
should be able to extract the proper device name by using it.