template: FileNotFoundError is actually a built in exception
However it is python3 only.
Differential Revision: https://phab.mercurial-scm.org/D11310
{header}
<title>Mercurial repository not found</title>
</head>
<body>
<div class="page_header">
<a href="{logourl}" title="Mercurial" style="float: right;">Mercurial</a> Not found: {repo|escape}
</div>
<div class="page_body">
The specified repository "{repo|escape}" is unknown, sorry.
<br/>
<br/>
Please go back to the <a href="{url|urlescape}">main repository list page</a>.
</div>
{footer}