Recent tags won't work on certain locales

Some locales use comma as decimal sign. This causes SQL error in tag query. In this line (actions/tag.php):

{{{
$tags->selectAdd(sprintf('sum(exp(-(now() - notice.created)/%f)) as weight', common_config('tag', 'dropoff')));
}}}

%f should be replaced with %s, since the whole parameter is a string anyways