[FIX] stock_account: average cost with foreign currency

Quants are created, and stock moves are updated, with the purchase
value converted at current rates.  However, the product average
was calculated before that value was retrieved.  This ensures
the correct value is retrieved for the average cost calculation
and will match the actual quants.

Fixes #12163
Closes #12164
opw-678511

addons/stock_account/stock_account.py

@@ -420,12 +420,14 @@ class stock_move(osv.osv):
                 else:
                     tmpl_dict[product_id] = 0
                     product_avail = qty_available
+                # if the incoming move is for a purchase order with foreign currency, need to call this to get the same value that the quant will use.
+                price_unit = self.pool.get('stock.move').get_price_unit(cr, uid, move, context=context)
                 if product_avail <= 0:
-                    new_std_price = move.price_unit
+                    new_std_price = price_unit
                 else:
                     # Get the standard price
                     amount_unit = product.standard_price
-                    new_std_price = ((amount_unit * product_avail) + (move.price_unit * move.product_qty)) / (product_avail + move.product_qty)
+                    new_std_price = ((amount_unit * product_avail) + (price_unit * move.product_qty)) / (product_avail + move.product_qty)
                 tmpl_dict[product_id] += move.product_qty
                 # Write the standard price, as SUPERUSER_ID because a warehouse manager may not have the right to write on products
                 ctx = dict(context or {}, force_company=move.company_id.id)