[14.0] purchase_stock if buy_rule is not found, seller is searched without company_id

[sergiocorato]

As the method returns in any case where buy_rule is not found, it should return before searching the seller.

Ref: https://github.com/OCA/OCB/blob/c88fd1610558046fb73209e3022e52a5dda96a31/addons/purchase_stock/models/stock_rule.py#L155C14-L158C14

Now it raises an error trying to open the stock orderpoint menu in a multi-company instance.

[sergiocorato]

I close this issue because the problem is that purchase_stock.route_warehouse0_buy route has been removed in all products in the migration process, I'll check it.