[FIX] website_sale: previous with adyen

When clicking on previous in Adyen payment, the customer will be
redirected in the shop and not in the confirmation page.

opw:645705

addons/website_sale/controllers/main.py

@@ -812,6 +812,8 @@ class website_sale(http.Controller):
 
         # clean context and session, then redirect to the confirmation page
         request.website.sale_reset(context=context)
+        if tx and tx.state == 'draft':
+            return request.redirect('/shop')
 
         return request.redirect('/shop/confirmation')