def _extract_next_filename(self):
        """
        changes metadata!
        """
        self.ensure_metadata()
        metadata, body = self[-1]
        metadata['section'] = sanitize_section(metadata['section'])
        metadata['root'] = root
        path = "{root}/Misc/NEWS.d/next/{section}/{date}.bpo-{bpo}.{nonce}.rst".format_map(metadata)
        for name in "root section date bpo nonce".split():
            del metadata[name]
        return path
changes metadata!