One thing I found is that in stock_account  in _store_average_cost_price it doesn't update the cost if there is any negative quant move. So I have my Product Category set to real price / perpetial valuation but some of the products there are consumable. So consumables always go in negative quantities (we don't control stock, incoming shipments etc. ).
That means if there is any consumable in the Bill of Materials there is no update of cost for any of the ingredients since it brakes the loop with return:

https://github.com/odoo/odoo/blob/10.0/addons/stock_account/models/stock.py#L224

Did I just found a bug in the code??? Shouldn't it consider if the product is stockable before making the check of negative quants?