code: def delete_commit_branches(self, enrich_backend):
          
          fltr = """
              "filter": [
                  {
                      "term": {
                          "origin": "%s"
                      }
                  }
              ]
          """ % self.perceval_backend.origin
  
          # reset references in enrich index
          es_query = """
              {
                "script": {
                  "source": "ctx._source.branches = new HashSet();",
                  "lang": "painless"
                },
                "query": {
                  "bool": {
                      %s
                  }
                }
              }
              """ % fltr
  
          index = enrich_backend.elastic.index_url
          r = self.requests.post(index + "/_update_by_query?refresh", data=es_query, headers=HEADER_JSON, verify=False)
          try:
              r.raise_for_status()
          except requests.exceptions.HTTPError:
              logger.error("Error while deleting branches on %s",
                           self.elastic.anonymize_url(index))
              logger.error(r.text)
              return
  
          logger.debug("Delete branches %s, index %s", r.text, self.elastic.anonymize_url(index))
docs: Delete the information about branches from the documents representing
          commits in the enriched index.
  
          :param enrich_backend: the enrich backend