[FIX] website_sale: sale_get_order force_create

Previously, if there was a sale_order_id but it was wrong,
like when the sale order was deleted for example, the function
didn't return a sale order, even with force_create=True.

It used to pass the first 'if' as sale_order_id had a value, so
no new sale order was created. However, as sometimes the id was
referring to a non-existant sale_order, a sale_order.exists() test
was used later, resulting in the function sometimes returning None,
even with force_create = True.

Proposed solution is to test the existence of the browse record with
the given id earlier, instead of testing the existence of the id itself.

addons/website_sale/models/sale_order.py

@@ -129,9 +129,9 @@ def sale_product_domain(self, cr, uid, ids, context=None):
     def sale_get_order(self, cr, uid, ids, force_create=False, code=None, update_pricelist=None, context=None):
         sale_order_obj = self.pool['sale.order']
         sale_order_id = request.session.get('sale_order_id')
-        sale_order = None
+        sale_order = sale_order_obj.browse(cr, SUPERUSER_ID, sale_order_id, context=context)
         # create so if needed
-        if not sale_order_id and (force_create or code):  
+        if not sale_order.exists() and (force_create or code):
             # TODO cache partner_id session
             partner = self.pool['res.users'].browse(cr, SUPERUSER_ID, uid, context=context).partner_id
 
@@ -146,15 +146,11 @@ def sale_get_order(self, cr, uid, ids, force_create=False, code=None, update_pri
                 values = sale_order_obj.onchange_partner_id(cr, SUPERUSER_ID, [], partner.id, context=context)['value']
                 sale_order_obj.write(cr, SUPERUSER_ID, [sale_order_id], values, context=context)
                 request.session['sale_order_id'] = sale_order_id
-        if sale_order_id:
+                sale_order = sale_order_obj.browse(cr, SUPERUSER_ID, sale_order_id, context=context)
+
+        if sale_order.exists():
             # TODO cache partner_id session
             partner = self.pool['res.users'].browse(cr, SUPERUSER_ID, uid, context=context).partner_id
-
-            sale_order = sale_order_obj.browse(cr, SUPERUSER_ID, sale_order_id, context=context)
-            if not sale_order.exists():
-                request.session['sale_order_id'] = None
-                return None
-
             # check for change of pricelist with a coupon
             if code and code != sale_order.pricelist_id.code:
                 pricelist_ids = self.pool['product.pricelist'].search(cr, SUPERUSER_ID, [('code', '=', code)], context=context)
@@ -197,6 +193,10 @@ def sale_get_order(self, cr, uid, ids, force_create=False, code=None, update_pri
             if (code and code != sale_order.pricelist_id.code) or sale_order.partner_id.id !=  partner.id:
                 sale_order = sale_order_obj.browse(cr, SUPERUSER_ID, sale_order.id, context=context)
 
+        else:
+            request.session['sale_order_id'] = None
+            return None
+
         return sale_order
 
     def sale_get_transaction(self, cr, uid, ids, context=None):