filemerge: use symlinkcheck for :merge and :union
This exposes a couple of bugs, both of which will be fixed in upcoming patches.
<table class="logEntry parity{parity}">
<tr>
<th class="label"><span class="age">{date|rfc822date}</span>:</th>
<th class="firstline">{desc|strip|firstline|escape|nonempty}</th>
</tr>
<tr>
<th class="revision">changeset {rev}:</th>
<td class="node"><a href="{url|urlescape}rev/{node|short}{sessionvars%urlparameter}">{node|short}</a></td>
</tr>
{parent%changelogparent}
{child%changelogchild}
{changelogtag}
<tr>
<th class="author">author:</th>
<td class="author">{author|obfuscate}</td>
</tr>
<tr>
<th class="date">date:</th>
<td class="date">{date|rfc822date}</td>
</tr>
<tr>
<th class="files"><a href="{url|urlescape}file/{node|short}{sessionvars%urlparameter}">files</a>:</th>
<td class="files">{files}</td>
</tr>
</table>