Link is not recognized when "Hide External Links From Search Engines" is unchecked

Summary of Bug

In Confluence 4.0 and 4.0.3, if the checkbox "Hide External Links From Search Engines" is unchecked, then all external links will no longer work. Once the checkbox is checked, then the external links will work fine.

How to Reproduce

1. When using either Confluence 4.0 or 4.0.3, enter an external link in a page.
2. Go to Confluence Admin > Security Configuration and uncheck the checkbox that says "Hide External Links From Search Engines"
3. The link in the page does not seem to be recognized as a link anymore, the user cannot click on the link

Findings

• When "Hide External Links From Search Engines" is enabled
  • how it rendered in HTML

    <div class="wiki-content" id="content-editable-container">
                               <p><a rel="nofollow" class="external-link" href="http://www.slysoft.com/en/download.html">Virtual CloneDrive</a></p>
        
            </div>
    

  • XHTML content

    <p><a href="http://www.slysoft.com/en/download.html">Virtual CloneDrive</a></p>
    

• When "Hide External Links From Search Engines" is disabled
  • how it rendered in HTML

    <div class="wiki-content" id="content-editable-container">
                               <p><a>Virtual CloneDrive</a></p>
        
            </div>
    

  • XHTML content

    <p><a href="http://www.slysoft.com/en/download.html">Virtual CloneDrive</a></p>
    

This issue does not seem to affect versions of Confluence prior to 4.0. Tested it on Confluence 3.5.13 and 3.4.9, external links works fine regardless whether or not external links is hidden from search engines.