Comment # 3 on bug 960074 from Matthias Sch�nemann

(In reply to Michael Chang from comment #1)
... 
> > I had to edit
> > grub.cfg to be able to start the old (broken) installation. 
> 
> Out of curious, how did you do that ? Is it chainloading the btrfs partition
> ?

Well, I added the following lines:
...
### END /etc/grub.d/90_persistent ###

### BEGIN Handarbeit ###
menuentry 'openSUSE Leap 42.1 kaputt'  --class opensuse --class gnu-linux
--class gnu --class os $menuentry_id_option
'gnulinux-simple-07808384-262d-4a8a-9c3d-da2ed2ac98f9' {
        load_video
        set gfxpayload=keep
        insmod gzio
        insmod part_msdos 
        insmod btrfs
        set root='hd0,msdos5'
        if [ x$feature_platform_search_hint = xy ]; then
          search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5
--hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 --hint='hd0,msdos5' 
07808384-262d-4a8a-9c3d-da2ed2ac98f9
        else
          search --no-floppy --fs-uuid --set=root
07808384-262d-4a8a-9c3d-da2ed2ac98f9
        fi
        echo    'Loading Linux 4.1.12-1-default ...'
        linux   /boot/vmlinuz-4.1.12-1-default
root=UUID=07808384-262d-4a8a-9c3d-da2ed2ac98f9  ${extra_cmdline}
resume=/dev/disk/by-uuid/57edc8bb-1fdb-487b-9f33-cef529a46f75 splash=silent
quiet showopts
        echo    'Loading initial ramdisk ...'
        initrd  /boot/initrd-4.1.12-1-default
}

### BEGIN snapshot Handarbeit ###
if [ -f "/.snapshots/grub-snapshot.cfg" ]; then
  source "/.snapshots/grub-snapshot.cfg"
fi
### END snapshot Handarbeit ###

This is the new entry, just changed to the correct UUIDs ... The last few lines
after Begin snapshot Handarbeit point to the new snapshots...

... 
> Please consider it as os-prober limitation, currently it will ignore
> snapshots except default subvolume.

Would be a nice to have addition but I guess not so many people do dual
installs -- yet. This might differ later on when more installations of
different releases coexist on more computers.