[17.0] subscription_oca - Uncontrolled changes of discount on product lines

[rickard-w]

Module

subscription_oca

Describe the bug

This behavior is present when "Advanced Price Rule" is activated.
If a product is defined in the pricelist, without any discount, but in subscription line is set to have some discount. When changing the product quantity in product line, the discount is automatic changed to that in the pricelist.

To Reproduce

Affected versions: 17.0

Steps to reproduce the behavior:

1. Activate Advanced Price Rule.
2. Create a post in the pricelist for a product. Define the products discount=0 (default).
3. Create a subcription. Place your product in the subscription lines. Change the discount for the product in this specific subscription to 10%.
4. Change the product quantity in subscription line.
5. Discount is now reset to 0%.

Expected behavior
Automatic updates of product lines should not happen when changing product quantity. This is only bound to create unnecessary errors.

Additional context
Bug can be recreated in runbot for verification.