[FIX] purchase: add the supplier list of the product in each company

Steps to reproduce the bug:
- Create a storable product “P1”
1:/
- Select the company A
- Create a purchase order:
    - product: “P1”
    - vendor: “V1”
    - confirm the PO
The vendor “V1” is added to the supplier list of “P1”

2:/
- Select the company B
- Create a purchase order:
    - product: “P1”
    - vendor: “V2”
    - confirm the PO

Problem:
The vendor “V2” is added to the list but “V1” is deleted from the list
in company A

The “seller_ids” field is in the “product.template” model, we try to
modify it in the “_add_supplier_to_product” function from the
“product_id”(product.product) field which inherits from the
“product.Template” model:
https://github.com/odoo/odoo/blob/3b88ed5ea458a37ee4d440f83bab45bd0fb13845/addons/purchase/models/purchase.py#L531-L532

So the function “inverse_related” will be called, in which the function
“__set__” will be triggered: In the values, the command for the create
will be added but the command for the set will be added as well while
it shouldn't. So in the `write_real` function a search will be done to
get all `product.supplierinfo` with the same product_tmpl_id:

https://github.com/odoo/odoo/blob/36544651f2049bcf18777091dbf02c9631b33243/odoo/fields.py#L4415-L4417

but as we are in sudo, those of company “A” will also be recovered, so
they will be unlinked since they are not in the command.set

opw-3251941

closes odoo/odoo#117985

X-original-commit: 78f803f3c1963711e2a5541f913f030da4f06fb7
Signed-off-by: William Henrotin (whe) <whe@odoo.com>
Signed-off-by: Djamel Touati (otd) <otd@odoo.com>

addons/purchase/models/purchase.py

@@ -548,7 +548,7 @@ class PurchaseOrder(models.Model):
                     'seller_ids': [(0, 0, supplierinfo)],
                 }
                 # supplier info should be added regardless of the user access rights
-                line.product_id.sudo().write(vals)
+                line.product_id.product_tmpl_id.sudo().write(vals)
 
     def action_create_invoice(self):
         """Create the invoice associated to the PO.

addons/purchase/tests/test_purchase.py

@@ -372,3 +372,50 @@ class TestPurchase(AccountTestInvoicingCommon):
         po.button_confirm()
 
         self.assertEqual(po.order_line.product_id.seller_ids.mapped('partner_id'), delivery_address)
+
+    def test_supplier_list_in_product_with_multicompany(self):
+        """
+        Check that a different supplier list can be added to a product for each company.
+        """
+        company_a = self.company_data['company']
+        company_b = self.company_data_2['company']
+        product = self.env['product.product'].create({
+            'name': 'product_test',
+            'type': 'product',
+        })
+        # create a purchase order in the company A
+        self.env['purchase.order'].with_company(company_a).create({
+            'partner_id': self.partner_a.id,
+            'order_line': [(0, 0, {
+                'product_id': product.id,
+                'product_qty': 1,
+                'product_uom': self.env.ref('uom.product_uom_unit').id,
+                'price_unit': 1,
+            })],
+        }).button_confirm()
+
+        self.assertEqual(product.seller_ids[0].partner_id, self.partner_a)
+        self.assertEqual(product.seller_ids[0].company_id, company_a)
+
+        # switch to the company B
+        self.env['purchase.order'].with_company(company_b).create({
+            'partner_id': self.partner_b.id,
+            'order_line': [(0, 0, {
+                'product_id': product.id,
+                'product_qty': 1,
+                'product_uom': self.env.ref('uom.product_uom_unit').id,
+                'price_unit': 2,
+            })],
+        }).button_confirm()
+        product = product.with_company(company_b)
+        self.assertEqual(product.seller_ids[0].partner_id, self.partner_b)
+        self.assertEqual(product.seller_ids[0].company_id, company_b)
+
+        # Switch to the company A and check that the vendor list is still the same
+        product = product.with_company(company_a)
+        self.assertEqual(product.seller_ids[0].partner_id, self.partner_a)
+        self.assertEqual(product.seller_ids[0].company_id, company_a)
+
+        product._invalidate_cache()
+        self.assertEqual(product.seller_ids[0].partner_id, self.partner_a)
+        self.assertEqual(product.seller_ids[0].company_id, company_a)