Clear contents of global hgrc for tests before running each test.
This fixes running test-mq-qdiff after test-mq, because of changed settings.
Content-type: text/html
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<link rel="icon" href="?static=hgicon.png" type="image/png">
<meta name="robots" content="index, nofollow" />
<link rel="stylesheet" href="?static=style.css" type="text/css" />