[IMP] sale: Allow partner removal if linked to draft/cancelled SO

closes odoo/odoo#116881

Taskid: 3233204
X-original-commit: 70686d7482d718776fc1ac9c4bad579e1b5c0f9f
Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>

addons/sale/models/res_partner.py

@@ -62,3 +62,14 @@ class ResPartner(models.Model):
         for res in group:
             partner = self.browse(res['partner_id'][0])
             partner.credit += res['amount_to_invoice']
+
+    def unlink(self):
+        # Unlink draft/cancelled SO so that the partner can be removed from database
+        self.env['sale.order'].sudo().search([
+            ('state', 'in', ['draft', 'cancel']),
+            '|', '|',
+            ('partner_id', 'in', self.ids),
+            ('partner_invoice_id', 'in', self.ids),
+            ('partner_shipping_id', 'in', self.ids),
+        ]).unlink()
+        return super().unlink()