# File lib/rbreadline.rb, line 5627
  def _rl_vi_save_insert(up)
    if (up.nil? || up.what != UNDO_INSERT)
      if (@vi_insert_buffer_size >= 1)
        @vi_insert_buffer[0] = 0.chr
      end
      return
    end
    start = up.start
    _end = up.end
    len = _end - start + 1
    @vi_insert_buffer = @rl_line_buffer[start,len-1]
  end