Switched to graphicsmagick to generate favicon. It doesn't support Microsoft ICO so generate PNG instead.
<!DOCTYPE html>
<html>
<head>
<meta name=viewport content="width=device-width, initial-scale=1">
<meta charset="utf-8">
<link href="favicon.png" rel="shortcut icon" type="image/png"/>
%(head)s
%(stylesheet)s
%(body_prefix)s
<div class="header container">
[ <a class="reference external" href="README.html">About</a>
| <a class="reference external" href="INSTALL.html">Download</a>
| <a class="reference external" href="MISC.html">Misc</a>
| <a class="reference external" href="STAT.html">Statistics</a>
| <a class="reference external" href="CHANGES.html">Changes</a>
| <a class="reference external" href="LICENSE.html">License</a>
| <a class="reference external" href="HACKING.html">Hacking</a> ]
</div>
<div class="header small container">
<p>
Compiled on <tt class="docutils literal"><span class="pre">{date}</span></tt>
from rev <tt class="docutils literal">{rev}</tt>.
</p>
<p>{warn1}</p>
<p>{warn2}</p>
</div>
%(body_pre_docinfo)s
%(docinfo)s
%(body)s
%(body_suffix)s