Well actually it shouldn't -- except for rEFInd the boot manager:
branding graphics within the build environment are used to add
a single background image to EFI/refind/icons/ thus the change.

Wonder how this got lost though as this screenshot:
http://en.altlinux.org/File:Altlinux-rescue-uefi-memtest86.jpg
clearly illustrates it was working back in December indeed!