change behaviour of SST-10: do not update manufacturing_number if not empty

ext/custom-addons/dp_custom/models/product.py

@@ -96,6 +96,8 @@ class ProductTemplate(models.Model):
         if product_template:
             # default_code may not be changed if there is already an inventory_line (in other company), so we remove it from the dict
             vals.pop('default_code',None)
+            if product_template['manufacturing_number']:
+                vals.pop('manufacturing_number',None)
             product_template.write(vals)
         else:
             if vals['active']: