Error in rendering conditional comments in Jade

I have added in my jade template this conditional comments taken from boostrap page

// HTML5 Shim and Respond.js IE8 support of HTML5 elements and media queries
// WARNING: Respond.js doesn't work if you view the page via file://
<!--[if lt IE 9]>
  <script src="https://oss.maxcdn.com/html5shiv/3.7.2/html5shiv.min.js"></script>
  <script src="https://oss.maxcdn.com/respond/1.4.2/respond.min.js"></script>
<![endif]-->

This is the way how it is rendered

<!-- HTML5 Shim and Respond.js IE8 support of HTML5 elements and media queries-->
<!-- WARNING: Respond.js doesn't work if you view the page via file://
<!--[if lt IE 9]>
   <script src="https://oss.maxcdn.com/html5shiv/3.7.2/html5shiv.min.js"></script>
   <script src="https://oss.maxcdn.com/respond/1.4.2/respond.min.js"></script>
<![endif]-->
    -->

As you may see it is not rendered correctly why? I have jade 1.5