Fix item based promotion issue

Steps to reproduce:

* Add something to cart, with some "order item adjustment" (promotion) applied.
* Edit the promotion settings, makes it ineligible.
* Update the cart, you will see the "order item adjustment" still attached. Ideally it should have been removed.

Thanks for reporting it @kayue!
@stloyd OK, thanks. This was enough for me to load fixtures. Not related to this fix anyway.