setup: use sys.executable to call hg
Executing ".\hg" does not work on Windows, but we can instead ask
Python to execute hg.
{header}
<title>Mercurial repository not found</title>
</head>
<body>
<h2>Mercurial repository not found</h2>
The specified repository "{repo|escape}" is unknown, sorry.
Please go back to the main repository list page.
{footer}