Steps to reproduce:
- Create a service that is subcontracted `service_to_purchase` = true
- Create a SO containing this service
- Go to the newly created RFQ
- Go to Alternatives -> Create Alternative and select a new vendor
- The alternative RFQ doesn't show a link to the SO, nor the SO to this
RFQ
Initially, when the alternative RFQ is created, only the `product_id`
and its quantity is copied to the new RFQ. Now we add the reference to
the SO as well so the RFQ is properly linked to the original SO.
Part of task-2985735
Part-of: odoo/odoo#106411
clesgow
3449a6d7c7