Tax rate of new determined Zone is not applied to existing order line

[martijnvdbrug]

Describe the bug
When the tax zone of an order is changed, via a custom TaxZoneStrategy, the new tax rate isn't applied to the existing order line.

To Reproduce
Steps to reproduce the behavior:

1. Setup your current channel to use NL
2. Create a Tax zone NL with rate 21%
3. Create a Tax Zone LU with rate 17%
4. Use the AddressBasedTaxZoneStrategy to determine zone based on address
5. Add an item to cart. See in admin it will have tax rate 21%
6. Set an address in Luxembourg on the order
7. See in the admin that the tax rate in the order summary is still 21%

Some findings:

• I have confirmed that this line does set the tax rate to 17%, but it's somehow not persisted.
• The orderLine.productVariant.taxRateApplied is 17%, but the orderLine.taxLines is [{ "description": "NL standaard", "taxRate": 21 }]
• Adding a new item, after the tax zone is changed, does set both orderLine.productVariant.taxRateApplied and orderLine.taxLines to 17%

It seems a determined

It becomes even stranger when I add a new item to cart: The order will now have both tax rates applied.

I am still investigating this.

Environment (please complete the following information):

• @vendure/core version: 3.1.1
• Nodejs version 18
• Database (mysql/postgres etc): MySQL

Additional context
Add any other context about the problem here.

[martijnvdbrug]

My bad, I was concurrently updating the shipping method and the shipping address on an order, which cause some weird race conditions somewhere.

Can not reproduce the issue with a single setOrderShippingAddress mutation