def on_cleanup_error(function, path, excinfo):
                click.secho("warning: failed to remove file or directory: {}\n"
                            "please delete it manually.".format(path),
                            fg="red")
def _raise_or_warn(self, warn_only, msg):
        if warn_only:
            self._warnings.append(msg)
        else:
            raise TransactionError(msg)