Thanks for taking your time to report this issue and help making Ubuntu better.
I can confirm that the non-existing repo is referenced in the copyright file in nova-lxd 16.0.0-0ubuntu1 on Ubuntu Artful. I found the same url in the control file, and it might be other places too. I assume the upstream repo has changed, but the packaging hasn't kept up.
Thanks for taking your time to report this issue and help making Ubuntu better.
I can confirm that the non-existing repo is referenced in the copyright file in nova-lxd 16.0.0-0ubuntu1 on Ubuntu Artful. I found the same url in the control file, and it might be other places too. I assume the upstream repo has changed, but the packaging hasn't kept up.