Unescaped escaped quotes

Trivial bug in tempate.php for theming the messages, approx line 673

foreach ($messages as $message) {
  $output .= ' <li class=\ "messages__item\ ">' . $message . "</li>\n";
}

i.e produces:

<li class=\ "messages__item\ ">abcd....</li>

PS: I had to add a space between the backslash and the double quote, Drupal formatter was converting this to just a double quote...