Bug#925556: use UUIDs 100% in grub, not /dev/sdX

[積丹尼 Dan Jacobson <jidanni@jidanni.org>]

retitle 925556 Use UUID, not sdX on grub linux lines
thanks

The problem simply turns out to be:
grub lines like
		linux	/boot/vmlinuz-4.9.0-8-amd64 root=/dev/sdb2 ro  quiet
are simply bound to fail:

When the computer boots, no matter when for the installer, or later, the
installed system, /dev/sdX could refer to something different.

So let's say there are two items plugged in when the grub.cfg is
created. And two items plugged in when the newly installed system is
booted. Well there is a 50% chance that the system won't boot.

With three items, only a 33% chance the system will boot.

https://www.gnu.org/software/grub/manual/grub/html_node/Device-map.html

Let's examine a proper linux line:

linux	/boot/vmlinuz-4.19.0-4-amd64 root=UUID=f19dae4b-fcb8-49eb-b43b-6f99597db52d ro quiet

I don't know why in the world your installer is still producing such bad
linux lines. Maybe it is because I did the install totally offline and
that's not what you test with.

Anyway, you need to find out why
GRUB_DISABLE_LINUX_UUID=true
is somehow apparently sadly in effect.

Actually it is only half in effect, as you see UUID entries, just not on
the linux line:

menuentry 'Debian GNU/Linux' --class debian --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-ee7dd9c6-9f5b-45bc-bf31-36123bd61588' {
	load_video
	insmod gzio
	if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
	insmod part_gpt
	insmod ext2
	set root='hd1,gpt2'
	if [ x$feature_platform_search_hint = xy ]; then
	  search --no-floppy --fs-uuid --set=root --hint-bios=hd1,gpt2 --hint-efi=hd1,gpt2 --hint-baremetal=ahci1,gpt2  ee7dd9c6-9f5b-45bc-bf31-36123bd61588
	else
	  search --no-floppy --fs-uuid --set=root ee7dd9c6-9f5b-45bc-bf31-36123bd61588
	fi
	echo	'Loading Linux 4.9.0-8-amd64 ...'
	linux	/boot/vmlinuz-4.9.0-8-amd64 root=/dev/sdb2 ro  quiet
	echo	'Loading initial ramdisk ...'
	initrd	/boot/initrd.img-4.9.0-8-amd64
}

For users reading this bug: use "e" from the grub boot screen to fix
e.g., sda2 to sdb2 or sdb2 to sda2, etc.

(The only other problem I had was the unrelated
Bug#926149: (AMD: Add nomodeset kernel parameter to avoid black screen))

Anyway this week I will delay final installation so I can assist further
if needed.