[REF] stock_account: _compute_average_price unit price rounding

Since the introduction of the stock valuation layer, unit_cost is
rounded in the company currency (actually it is NOT because of an ORM
bug that will be fixed later). With the test introduced at [0], fixing
that ORM bug shows we have a rounding issue (27.02 instead of 27) due to
the company currency rounding on the unit_cost. Since the logic of the
anglo saxon will probably always give some rounding issue (we always
return a price unit that will be multiply by the invoiced quantity)
recomputing a not rounded price unit by using the not rounded value with
the not rounded quantity seems a good enough compromise.

[0] 13a535a091

closes odoo/odoo#35384

Signed-off-by: Simon Lejeune (sle) <sle@openerp.com>

addons/stock_account/models/product.py

@@ -585,7 +585,7 @@ class ProductProduct(models.Model):
             qty_taken_on_candidate = min(qty_to_take_on_candidates, candidate_quantity)
 
             qty_to_take_on_candidates -= qty_taken_on_candidate
-            tmp_value += qty_taken_on_candidate * candidate.unit_cost
+            tmp_value += qty_taken_on_candidate * (candidate.value / candidate.quantity)
             if float_is_zero(qty_to_take_on_candidates, precision_rounding=candidate.uom_id.rounding):
                 break