def process_spider_output(self, response, result, spider):
        """Store page tag details if page clustering was not available."""
        saved = False
        for out in result:
            if (not saved and self.clustering_enabled and
                    hasattr(out, 'get') and
                    out.get('_template_cluster') == _CLUSTER_NA):
                key = request_fingerprint(response.request)
                logging.debug('Saving %s for clustering on next crawl',
                              response.request)
                self.db[key] = json.dumps([response.body_as_unicode(),
                                           response.encoding])
                saved = True
            yield out
Store page tag details if page clustering was not available.
slybot/slybot/clustering.py