Notice when ordering again

I have found a little bug which happens in the following situation:
– Bundle product with multiple optional childs
– Add to cart with optional A, B and C
– Add to cart with optional A, D and E
– Reorder through my account
– A notice “1 item from your previous order is currently unavailable and could not be added to your cart” is shown, however all items are added to the cart

I have done some debugging and found what is causing this issue. Within /woocommerce/includes/class-wc-cart-session.php in the function ‘populate_cart_from_order’ they generate a cart ID:

$cart_id = WC()->cart->generate_cart_id( $product_id, $variation_id, $variations, $cart_item_data );

In my situation, the cart ID for optional A (in both order lines) is exactly the same, because the $cart_item_data is exactly the same. WooCommerce then counts the ‘new’ $cart array, filled using the $cart_id and compares this to the original $order_items.

The cart_item_data contains two fields:
woosb_order_again: yes
woosb_parent_id: 123

Because they both have the same parent product it’s not unique in this case. It would be better to add the woosb_parent_key to the order items, which is also used within the cart while ordering.