- Add a product (imac 1.799$) and a promo code (eg: 10%) in your cart
- Go to checkout (/shop/cart). You now see 1,619.10 Total and 179.90 discount
- Change product qty (eg: 2)
- Subtotal is now 2x 1.799 - 179.90 instead of 2x 1.799 - 2x 179.90
- Reward line total (discount) is still the same amount (10% on 1 ipad)
Now, we will recompute the discount price based on the entire cart
Note: This behavior was wanted and comes from this commit #87d542
But for the shop, we need to have the reward line being updated on the fly or
it wont make sense for the end user.
This closes #ee4be7a532dd707a0cd19c766dc8e8537dcda242