The following line of HTML code is malformed. The <a> tag shouldn't have a '/' character at the end. This markup is usually for tags like <br /> and <img /> . I found this specifically because the apache module mod_proxy_html interperates this tag as a single tag and breaks the HTML (where browsers would normally ignore this error). This line of code only appears when viewing an issue.

The offending code:

<tr>
<td valign="top"><b>Watchers:</b></td>
<td valign="top">
0
 <span class="small">(<a id="view_watchers" href="/secure/ManageWatchers!default.jspa?id=20479" />View</a>)</span>
</td>
</tr>

The fix:
<tr>
<td valign="top"><b>Watchers:</b></td>
<td valign="top">
0
 <span class="small">(<a id="view_watchers" href="/secure/ManageWatchers!default.jspa?id=20479">View</a>)</span>
</td>
</tr>