revset: prevent crash caused by empty group expression while optimizing "and"
An empty group expression "()" generates None in AST, so the optimizer have
to test it before destructuring a tuple. The error message, "missing argument",
is somewhat obscure, but it should be better than crash.
<tr>
<td class="age">{date|rfc822date}</td>
<td class="author">{author|person}</td>
<td class="description">
<a href="{url|urlescape}rev/{node|short}{sessionvars%urlparameter}">{desc|strip|firstline|escape|nonempty}</a>
{inbranch%changelogbranchname}{branches%changelogbranchhead}{tags%changelogtag}{bookmarks%changelogtag}
</td>
</tr>