$searchCondition['where'] .= ' AND (stock > 0 OR stock_unlimited = 1)';

LC_Page_Products_List.php
$order = <<< __EOS__
    (
        SELECT
            T3.rank
        FROM
            $dtb_product_categories T2
            JOIN dtb_category T3
                USING (category_id)
            WHERE T2.product_id = alldtl.product_id
            ORDER BY T3.rank DESC, T2.rank DESC
            LIMIT 1
    ) DESC
   ,(
        SELECT
            T2.rank
        FROM
            $dtb_product_categories T2
            JOIN dtb_category T3
293行目→       USING (category_id)
            WHERE T2.product_id = alldtl.product_id
            ORDER BY T3.rank DESC, T2.rank DESC
            LIMIT 1
    ) DESC
    ,product_id
__EOS__;