I get a 502 Bad Gateway error about 25% of the times I am loading a page at http://quarry.wmflabs.org/ This happens at any page. When trying to do a "reload" of a single page, it failed 5 times of 20:
<html>
<head><title>502 Bad Gateway</title></head>
<body bgcolor="white">
<center><h1>502 Bad Gateway</h1></center>
<hr><center>nginx/1.4.6 (Ubuntu)</center>
</body>
</html>
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