code: def fetch_track_items(upstream_file_url, data_source):
      
  
      track_uris = []
      req = requests_ses.get(upstream_file_url)
      try:
          req.raise_for_status()
      except requests.exceptions.HTTPError as ex:
          logger.warning("Can't get gerrit reviews from %s", upstream_file_url)
          logger.warning(ex)
          return track_uris
  
      logger.debug("Found reviews to be tracked in %s", upstream_file_url)
  
      lines = iter(req.text.split("\n"))
      for line in lines:
          if 'url: ' in line:
              dso = next(lines).split('system: ')[1].strip('\n')
              if dso == data_source:
                  track_uris.append(line.split('url: ')[1].strip('\n'))
      return track_uris
docs: The file format is:
  
      # Upstream contributions, bitergia will crawl this and extract the relevant information
      # system is one of Gerrit, Bugzilla, Launchpad (insert more)
      ---
      -
        url: https://review.openstack.org/169836
        system: Gerrit