convert_git: avoid returning two entries for the same file in getchanges
This could happen in merge changesets if the merged file was different
from both parents.
#header#
<title>Mercurial repositories index</title>
</head>
<body>
<h2>Mercurial Repositories</h2>
<table>
<tr>
<td><a href="?sort=#sort_name#">Name</a></td>
<td><a href="?sort=#sort_description#">Description</a></td>
<td><a href="?sort=#sort_contact#">Contact</a></td>
<td><a href="?sort=#sort_lastchange#">Last change</a></td>
<td> </td>
<tr>
#entries%indexentry#
</table>
#footer#