[kovidgoyal]

There are lots of invalid comments in that raw html, for example,

    <!--[if lte IE 8]>
  
<div data-module-id="6" data-module-name="article.app/lib/module/ieWarning" data-module-zone="ie_warning" class="zonedModule">
<div class="ie-flag">
  <button class="ie-button"></button>

  <div class="ie-warning-wrapper">
    <p><span id="warning-label">BROWSER UPDATE</span> To gain access to the full experience, please upgrade your browser: </p>
    <ul>
      <li><a href="https://www.google.com/intl/en_us/chrome/browser/">Chrome</a> | </li>
      <li><a href="http://support.apple.com/downloads/#safari">Safari</a> | </li>
      <li><a href="https://www.mozilla.org/en-US/firefox/new/">Firefox</a> | </li>
      <li><a href="http://windows.microsoft.com/en-us/internet-explorer/download-ie">Internet Explorer</a></li>
    </ul><br>
    <p><span id="warning-note">Note: If you are running Internet Explorer 9 and above, make sure it is not in compatibility mode</span></p>
  </div>
</div>

</div> <!-- data-module-name="article.app/lib/module/ieWarning" -->

    <![endif]-->

Note the improper nesting of comments. And then this:

         <![if ! lte IE 8]>
        <span class="image-enlarge">
          ENLARGE
        </span>
        <![endif]>

The following should take care of it:

    preprocess_regexps = [
        (re.compile(r'<!--\[if lte IE 8\]>.+?<!\[endif\]-->', re.DOTALL), lambda m: ''),
        (re.compile(r'<!\[if ! lte IE 8\]>.+?<!\[endif\]>', re.DOTALL), lambda m:''),
    ]