def unlock_repo(self, repo_name):
        """
        :calls: `DELETE /user/migrations/:migration_id/repos/:repo_name/lock`_
        :param repo_name: str
        :rtype: None
        """
        assert isinstance(repo_name, (str, unicode)), repo_name
        headers, data = self._requester.requestJsonAndCheck(
            "DELETE",
            self.url + "/repos/" + repo_name + "/lock",
            headers={
                "Accept": Consts.mediaTypeMigrationPreview
            }
        )