+
+I installed mathjax as described here http://stackoverflow.com/a/8444409/406686.
+
+The rebuild of an old site containing math is missing the following lines:
+
+<script src="/mathjax/MathJax.js?config=TeX-AMS_HTML-full" type="text/javascript"></script>
+</head>
+<body>
+<noscript>
+<div style="color:#CC0000; text-align:center">
+<b>Warning: <a href="http://www.mathjax.org/">MathJax</a>
+requires JavaScript to process the mathematics on this page.<br>
+If your browser supports JavaScript, be sure it is enabled.</b>
+</div>
+<hr>
+</noscript>