docs: def add_tarball(self, tarball, package):
          """Add a tarball, possibly creating the directory if needed."""
          if tarball is None:
              logger.error(
                  "No tarball found for %s: probably a renamed project?",
                  package)
              return
          target_dir = os.path.join(self.root_directory, package)
          if not os.path.exists(target_dir):
              os.mkdir(target_dir)
              logger.info("Created %s", target_dir)
          logger.info("Copying tarball to %s", target_dir)
          shutil.copy(tarball, target_dir)