def upload(self, cmd: str, meta: dict):
        """Push the current state of the registry to Git."""
        index = os.path.join(self.cached_repo, self.INDEX_FILE)
        if os.path.exists(index):
            os.remove(index)
        self._log.info("Writing the new index.json ...")
        with open(index, "w") as _out:
            json.dump(self.contents, _out)
        git.add(self.cached_repo, [index])
        message = self.COMMIT_MESSAGES[cmd].format(**meta)
        if self.signoff:
            global_conf_path = os.path.expanduser("~/.gitconfig")
            if os.path.exists(global_conf_path):
                with open(global_conf_path, "br") as _in:
                    conf = ConfigFile.from_file(_in)
                    try:
                        name = conf.get(b"user", b"name").decode()
                        email = conf.get(b"user", b"email").decode()
                        message += self.DCO_MESSAGE.format(name=name, email=email)
                    except KeyError:
                        self._log.warning(
                            "Did not find name or email in %s, committing without DCO.",
                            global_conf_path)
            else:
                self._log.warning("Global git configuration file %s does not exist, "
                                  "committing without DCO.", global_conf_path)
        else:
            self._log.info("Committing the index without DCO.")
        git.commit(self.cached_repo, message=message)
        self._log.info("Pushing the updated index ...")
        # TODO: change when https://github.com/dulwich/dulwich/issues/631 gets addressed
        git.push(self.cached_repo, self.remote_url, b"master")
        if self._are_local_and_remote_heads_different():
            self._log.error("Push has failed")
            raise ValueError("Push has failed")
Push the current state of the registry to Git.