If a boot option doesn't refer to a valid file for the kernel/initrd,
ignore it. Such an option is never bootable, because we would fail to
find the kernel/initrd. This could happen if the path contained GRUB
variables, or specified a device that wasn't /boot, etc.
This is checked before expanding GRUB variables. It's unlikely that
any kernel/initrd path containing variables would end up working when
all variables expand to nothing (since we do not handle GRUB
variables).
Signed-off-by: Jonathon Hall <jonathon.hall@puri.sm>
698360199c