chmod: cannot access '/boot/vmlinuz*' if no kernel is installed in container.

[chantra]

If the container does not have any /boot/vmlinuz* file, preepare-rootfs will fail with:

Disk image: /tmp/root.img
vmlinux_setup - Preparing Linux image
  
  chmod: cannot access '/boot/vmlinuz*': No such file or directory
  libguestfs: error: /usr/bin/supermin exited with error status 1.
  To see full error messages you may need to enable debugging.
  Do:
    export LIBGUESTFS_DEBUG=1 LIBGUESTFS_TRACE=1
  and run the command again.  For further information, read:
    http://libguestfs.org/guestfs-faq.1.html#debugging-libguestfs
  You can also run 'libguestfs-test-tool' and post the *complete* output
  into a bug report or message to the libguestfs mailing list.
  Error: Process completed with exit code 2.

This is due to

ci/prepare-rootfs/run.sh

Line 344 in e669be2

sudo chmod +r /boot/vmlinuz* || true

Installing linux-image-generic in the container works.

apt install linux-image-generic

but we should re-assess if this is really needed still.

[thefallentree]

i don't know why this is needed: I don't think we do: we should simply delete that chmod