Bug#605562: installation-report: Installation from usb stick lead, to unbootable system (und unbootable usb stick)

[Joachim Schleicher <joachim@dormettingen.de>]

severity 568529 serious
tags 568529 - moreinfo
thanks

Hello,
now we have five different people reporting that bug. Most of them set a severity of serious or above.
Therefore I increased the severity: Makes package unfit for release in my opinion.

Some more additional information from the installer environment; I ran a shell before installing grub
(Expert install; another empty hard-drive as in the report above):
<ash>
BusyBox v1.17.1 (Debian 1:1.17.1-8) built-in shell (ash)
Enter 'help' for a list of built-in commands.

~ # mount
rootfs on / type rootfs (rw)
none on /proc type proc (rw,relatime)
none on /sys type sysfs (rw,relatime)
tmpfs on /dev type tmpfs (rw,relatime,mode=755)
none on /dev/prs type devpts (rw,relatim,gid=5,mode=620,ptmxmode=000)
/dev/sda1 on /hd-media type vfat 
(ro,relatime,fmask=0022,dmask=0022,codepage=cp437,iocharset=utf8,shotname=mixed,errors=remount-ro)
/dev/loop0 on /cdrom type iso9660 (ro,relatime)
/dev/sdb1 on /target type ext3 (rw,relatime,errors=remount-ro,data=ordered)
/dev/sdb6 on /target/home type ext3 (rw, relatime,errors=continue,data=ordered)
/dev/sdb1 on /dev/.static/dev type ext3 (rw,relatime,errors=remount-ro,data=ordered)
tmpfs on /target/dev/ type tmpfs (rw,relatime,mode=755)
/dev/loop0 on /target/media/cdrom0 type iso9660 (ro,relatime)

~ # chroot /target grub-mkdevicemap --no-floppy -m -
(hd0)	/dev/disk/by-id/usb-SanDisk_Cruzer_Blade_20053349610A41A2F01B-0:0
(hd1)	/dev/disk/by-id/ata-FUJITSU_M1623TAU_08316741

~ # readlink -f $(chroot /target grub-mkdevicemap --no-floppy -m - | head -n1 | cut -f2)
/dev/sda
<ash>

Do you need addional information?

My interpretation (grub-installer Line 538-570):
grub-installer uses the first device and double-checks that this is not /cdrom.
But that check is false, because /cdrom is /dev/loop0.
We should additionally check the "device-to-disk()" of /hd-media in the same manner as /cdrom.
That would install grub on the right device. Is it a problem when after reboot at an update the usb-stick is 
no longer present and the hard drive is named /dev/sda then?
What do you think?

Best Regards
Joachim