treediscovery: update test expectation
I'm not sure why this needs an update, but the test passes for me both
pure and non-pure.
Differential Revision: https://phab.mercurial-scm.org/D860
<table class="slogEntry parity{parity}">
<tr>
<td class="age">{date|rfc822date}</td>
<td class="author">{author|person}</td>
<td class="node"><a href="{url|urlescape}rev/{node|short}{sessionvars%urlparameter}">{desc|strip|firstline|escape|nonempty}</a></td>
</tr>
</table>