public function getQuoteCouponCode(Mage_Sales_Model_Quote $quote, Mage_SalesRule_Model_Rule $rule)
    {
        /** @var string */
        $codeAppliedToQuote = $quote->getCouponCode();
        /** @var string */
        $codeInRule = $rule->getCouponCode();
        return $codeAppliedToQuote === $codeInRule
            ? $codeAppliedToQuote
            : $this->getCodeFromCouponPool($rule, $codeAppliedToQuote);
    }