code: def get_build_info_for_index(self, build_index=None):
          
          url = urljoin(self.base_url, self.build_list_regex)
  
          self.logger.info('Retrieving list of builds from %s' % url)
          parser = self._create_directory_parser(url)
          parser.entries = parser.filter(r'^\d+$')
  
          if self.timestamp:
              # If a timestamp is given, retrieve the folder with the timestamp
              # as name
              parser.entries = self.timestamp in parser.entries and \
                  [self.timestamp]
  
          elif self.date:
              # If date is given, retrieve the subset of builds on that date
              parser.entries = filter(self.date_matches, parser.entries)
  
          if not parser.entries:
              message = 'No builds have been found'
              raise errors.NotFoundError(message, url)
  
          self.show_matching_builds(parser.entries)
  
          # If no index has been given, set it to the last build of the day.
          if build_index is None:
              # Find the most recent non-empty entry.
              build_index = len(parser.entries)
              for build in reversed(parser.entries):
                  build_index -= 1
                  if not build_index or self.is_build_dir(build):
                      break
  
          self.logger.info('Selected build: %s' % parser.entries[build_index])
  
          return (parser.entries, build_index)
docs: Get additional information for the build at the given index.