Comment 6 for bug 1768968

> I suspect some ISO build tools are broken at some point

I would contend that if the ISO boots the way it was intended to (from BIOS or UEFI), it's working fine. Note that "grml-rescueboot", per its own definition, is for booting GRML ISOs, not just any random ISO. Maybe there's something we can do to make them get along, but it's hardly a primary goal of either project.