mercurial/templates/atom/filelog.tmpl

extensions: factor import error reporting out

To clarify third party extensions lookup, we are about to add a third place
where extensions are searched for. So we factor the error reporting logic out to
be able to easily reuse it in the next patch.

{header}
 <id>{urlbase}{url|urlescape}atom-log/tip/{file|escape}</id>
 <link rel="self" href="{urlbase}{url|urlescape}atom-log/tip/{file|urlescape}"/>
 <title>{repo|escape}: {file|escape} history</title>
 {latestentry%feedupdated}

{entries%changelogentry}
</feed>