code: def _update_release_content(self, release, content):
          
          if release.body:
              new_body = []
              current_parser = None
              is_start_line = False
              for parser in self.parsers:
                  parser.replaced = False
  
              # update existing sections
              for line in release.body.splitlines():
  
                  if current_parser:
                      if current_parser._is_end_line(current_parser._process_line(line)):
                          parser_content = current_parser.render()
                          if parser_content:
                              # replace existing section with new content
                              new_body.append(parser_content + "\r\n")
                          current_parser = None
  
                  for parser in self.parsers:
                      if (
                          parser._render_header().strip()
                          == parser._process_line(line).strip()
                      ):
                          parser.replaced = True
                          current_parser = parser
                          is_start_line = True
                          break
                      else:
                          is_start_line = False
  
                  if is_start_line:
                      continue
                  if current_parser:
                      continue
                  else:
                      # preserve existing sections
                      new_body.append(line.strip())
  
              # catch section without end line
              if current_parser:
                  new_body.append(current_parser.render())
  
              # add new sections at bottom
              for parser in self.parsers:
                  parser_content = parser.render()
                  if parser_content and not parser.replaced:
                      new_body.append(parser_content + "\r\n")
  
              content = u"\r\n".join(new_body)
  
          return content
docs: Merge existing and new release content.