[FIX] sale: correctly set default fiscal position on invoice

default fiscal position of previously selected partner is not getting
cleared up when current selected partner doesn't have a default one

task: 2071608
closes: #37231

$XX

closes odoo/odoo#37728

X-original-commit: bce4bcc61196bbeafb41f77b7a95051b225faea6
Signed-off-by: Quentin De Paoli (qdp) <qdp@openerp.com>

addons/sale/models/account_invoice.py

@@ -45,12 +45,12 @@ class AccountMove(models.Model):
     @api.onchange('partner_id')
     def _onchange_partner_id(self):
         # OVERRIDE
-        res = super(AccountMove, self)._onchange_partner_id()
-
         # Recompute 'partner_shipping_id' based on 'partner_id'.
         addr = self.partner_id.address_get(['delivery'])
         self.partner_shipping_id = addr and addr.get('delivery')
 
+        res = super(AccountMove, self)._onchange_partner_id()
+
         # Recompute 'narration' based on 'company.invoice_terms'.
         if self.type == 'out_invoice':
             self.narration = self.company_id.with_context(lang=self.partner_id.lang).invoice_terms