[FIX] website_sale: fix concurrent update

Since forward-port, `/sale/get_combination_info_website` and `_cart_update`
would lead to a concurrency error.

Indeed, the session would not have an order_id at first. Then both rpc would
be sent at the same time:
- `cart_update` would create an order and add it in the session
- `/sale/get_combination_info_website` would end up calling `_compute_cart_qty`
which would call `sale_get_order` and would set the `sale_order_id` to none,
just aftet the `_compute_cart_qty` would actually add an order in the
session, simultaneously.

closes odoo/odoo#33993

Signed-off-by: Christophe Simonis <chs@odoo.com>


Co-authored-by: Romain Derie <rde@odoo.com>
Co-authored-by: Christophe Simonis <chs@odoo.com>
Co-authored-by: Sébastien Theys <seb@odoo.com>

addons/website_sale/controllers/main.py

@@ -390,13 +390,13 @@ class WebsiteSale(http.Controller):
                 return request.render('website.404')
             if abandoned_order.state != 'draft':  # abandoned cart already finished
                 values.update({'abandoned_proceed': True})
-            elif revive == 'squash' or (revive == 'merge' and not request.session['sale_order_id']):  # restore old cart or merge with unexistant
+            elif revive == 'squash' or (revive == 'merge' and not request.session.get('sale_order_id')):  # restore old cart or merge with unexistant
                 request.session['sale_order_id'] = abandoned_order.id
                 return request.redirect('/shop/cart')
             elif revive == 'merge':
                 abandoned_order.order_line.write({'order_id': request.session['sale_order_id']})
                 abandoned_order.action_cancel()
-            elif abandoned_order.id != request.session['sale_order_id']:  # abandoned cart found, user have to choose what to do
+            elif abandoned_order.id != request.session.get('sale_order_id'):  # abandoned cart found, user have to choose what to do
                 values.update({'access_token': abandoned_order.access_token})
 
         if order:

addons/website_sale/models/website.py

@@ -260,7 +260,8 @@ class Website(models.Model):
         sale_order = self.env['sale.order'].sudo().browse(sale_order_id).exists() if sale_order_id else None
 
         if not (sale_order or force_create or code):
-            request.session['sale_order_id'] = None
+            if request.session.get('sale_order_id'):
+                request.session['sale_order_id'] = None
             return self.env['sale.order']
 
         if self.env['product.pricelist'].browse(force_pricelist).exists():