url: pass str to pathname2url
This is needed to appease Python 3.
This fixes test-extdata.t and test-url-download.t on Python 3
on Windows.
Differential Revision: https://phab.mercurial-scm.org/D8335
{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 <a href="{url|urlescape}">main repository list page</a>.
{footer}