I'd glad to amend patch, if there are suggestions how to generalize it and
improve "create boot image" process for distros that doesn't have
grub2-mkrescue.
A reusable tool/script would be useful even outside virt-test. Anybody
who uses -kernel/-initrd today may want a more efficient solution (IIRC,
virt-install uses -kernel/-initrd when installing from a Fedora
repository URL).
But if we made that an independent tool we would have the additional
problem of having the new tool packaged and installed on the host. So
having something specific inside virt-test makes sense by now.