Comment 14 for bug 1269992

Further no more working function found here -> all relevant systems after upgrade involved!

The background picture is stated in the '/etc/default/grub'
 -> GRUB_GFXMODE=1024x768
 -> GRUB_BACKGROUND="/usr/share/backgrounds/gnome/Stones.jpg"

Both versions 2.00-22 as well as 2.02~beta2-4 output of 'sudo update-grub' look identical:

/quote
**** part of grub.cfg -> /etc/grub.d/00_header ****
....
....
insmod jpeg
background_image -m stretch /@/usr/share/backgrounds/gnome/Stones.jpg

**** part of grub.cfg -> /etc/grub.d/05_debian_theme ****
....
....
insmod jpeg
if background_image /@/usr/share/backgrounds/gnome/Stones.jpg; then
  true
else
....
/unquote

No background picture will be shown in the '2.02~beta2-4' grub menu !?! Downgrading grub-packages the choosen picture will be shown again. No changes have been made in between on configuration.

Using the (long) configuration by '/boot/grub/themes/<name>' will work without restrictions.