[FIX] stock_dropshipping: do not merge PO lines coming from a SO

Fine tuning of commit b9e3c153, for the same use-case.
The route may not be passed in values, in which case the bug is still present.
There are two ways to go around that.
We could add the stock.rule in values, which contains the route.
The solution we adopt here is to use the sale_line_id field on the purchase line
If it is present, it was added through _prepare_purchase_order_line,
and thus we want to keep track of the origin.

opw 1957701

closes odoo/odoo#32683

Signed-off-by: Nans Lefebvre (len) <len@odoo.com>

addons/stock_dropshipping/models/purchase.py

@@ -17,7 +17,9 @@ class PurchaseOrderLine(models.Model):
         return res
 
     def _merge_in_existing_line(self, product_id, product_qty, product_uom, location_id, name, origin, values):
-        if values.get('route_ids') and values['route_ids'] == self.env.ref('stock_dropshipping.route_drop_shipping'):
+        if values.get('sale_line_id') and values['sale_line_id'] != self.sale_line_id.id:
+            # if this is defined, this is a dropshipping line, so no
+            # this is to correctly map delivered quantities to the so lines
             return False
         return super(PurchaseOrderLine, self)._merge_in_existing_line(
             product_id=product_id, product_qty=product_qty, product_uom=product_uom,

addons/stock_dropshipping/tests/test_dropship.py

@@ -43,3 +43,19 @@ class TestDropship(TransactionCase):
         # Update qty on SO and check PO
         so.order_line.product_uom_qty = 2.00
         self.assertAlmostEqual(po_line.product_qty, 2.00)
+
+        # Create a new so line
+        sol2 = self.env['sale.order.line'].create({
+            'order_id': so.id,
+            'name': prod.name,
+            'product_id': prod.id,
+            'product_uom_qty': 3.00,
+            'product_uom': prod.uom_id.id,
+            'price_unit': 12,
+        })
+        # there is a new line
+        pol2 = po.order_line - po_line
+        # the first line is unchanged
+        self.assertAlmostEqual(po_line.product_qty, 2.00)
+        # the new line matches the new line on the so
+        self.assertAlmostEqual(pol2.product_qty, sol2.product_uom_qty)