The code was assuming that the first line of output was something like
this (and this is the case of the cd builder machine that uses a custom
built xorriso):
> GNU xorriso 1.2.6 : RockRidge filesystem manipulator, libburnia project.
But the output of the version packaged in Debian does not have the GNU
string:
> xorriso 1.3.2 : RockRidge filesystem manipulator, libburnia project.
We fix this issue by extracting the version from the line starting with
"xorriso version" which does not have this discrepancy.
debian-installer now has extra steps to create a grub_embed file which
can be passed to xorriso's --embedded-boot option. Add corresponding
code in debian-cd to use it to make images USB bootable.
Patch from Samuel Thibault.