[Plugin: WP-DB-Backup] Can't exclude both spam and post revisions

I’m looking through the code of wp-db-backup.php. As far as I can tell, the following code won’t allow the user to exclude both spam comments and post revisions, even if he’s checked both boxes in the interface:

if ( is_array($excs[‘spam’] ) && in_array($table, $excs[‘spam’]) ) {
$where = ‘ WHERE comment_approved != “spam”‘;
} elseif ( is_array($excs[‘revisions’] ) && in_array($table, $excs[‘revisions’]) ) {
$where = ‘ WHERE post_type != “revision”‘;
}

One WHERE clause or the other will be executed in the generated SQL string, but not both.