404.html (16 lines of code) (raw):
<html>
<head>
<script type="text/javascript" charset="utf-8">
var shortLinks = {
repo: 'https://github.com/facebook/hhvm/',
fb: 'https://facebook.com/hhvm/',
};
var shortLink = window.location.pathname.split('/')[1];
if (shortLinks.hasOwnProperty(shortLink)) {
var loc = shortLinks[shortLink];
window.location.href = loc;
}
</script>
</head>
<body>Page not found.</body>
</html>