convert: Use clone's behaviour for the default destionation name.
Adjusted the documentation for this and for the fact that the destionation is
created even if a name is specified.
#header#
<title>Mercurial Error</title>
</head>
<body>
<h2>Mercurial Error</h2>
<p>
An error occured while processing your request:
</p>
<p>
#error|escape#
</p>
#footer#