**Impacted versions:** 8.0

**Steps to reproduce:**
To reproduce it is necessary the fifo configuration in the assignation of quants in moves.

- Create a sale order with two lines of the same product, one of that line with a route that generate moves between warehouse.

<img width="1231" alt="skitch 65" src="https://cloud.githubusercontent.com/assets/11341058/24102907/d575a638-0d53-11e7-922e-a3f034d43e94.png">

The route used has three pull rules:

1. From Stock Warehouse_1 to Virtual Locations/Inter Company Transit
2. From Virtual Locations/Inter Company Transit to Stock Warehouse_2
3. From Stock Warehouse_2 to Customers

<img width="1224" alt="skitch 66" src="https://cloud.githubusercontent.com/assets/11341058/24103147/b7c2bfbc-0d54-11e7-955c-87247a10e0bd.png">

- Confirm the sale order. It must be created three pickings:

<img width="1226" alt="skitch 67" src="https://cloud.githubusercontent.com/assets/11341058/24103498/d90c9b38-0d55-11e7-97ff-f986df8cdd9b.png">

- Transfer first two pickings.

<img width="1230" alt="skitch 70" src="https://cloud.githubusercontent.com/assets/11341058/24104496/b7b0be8a-0d58-11e7-89a2-4331fceec1d8.png">

- Before transfer third picking, review that one move has reserved the quant correctly because was reserved from the previous pickings.

<img width="1215" alt="skitch 68" src="https://cloud.githubusercontent.com/assets/11341058/24103908/23952cc8-0d57-11e7-9346-bd48d7edb54a.png">

**Current behavior:**

When check availability of this third picking, the quant already reserved is moved to the other move.

<img width="1264" alt="skitch 69" src="https://cloud.githubusercontent.com/assets/11341058/24104056/8be11616-0d57-11e7-8763-a90507315b19.png">
 
**Expected behavior:**

When check availability of this third picking, the moves already reserved must not be altered.


'''method that creates the link between a given operation and move(s) of given product, for the given quantity.
            Returns True if it was possible to create links for the requested quantity (False if there was not enough quantity on stock moves)'''
            qty_to_assign = qty
            prod_obj = self.pool.get("product.product")
            product = prod_obj.browse(cr, uid, product_id)
            rounding = product.uom_id.rounding
            qtyassign_cmp = float_compare(qty_to_assign, 0.0, precision_rounding=rounding)
            if prod2move_ids.get(product_id):
                while prod2move_ids[product_id] and qtyassign_cmp > 0:
                    qty_on_link = _create_link_for_index(operation_id, 0, product_id, qty_to_assign, quant_id=False)
                    qty_to_assign -= qty_on_link
                    qtyassign_cmp = float_compare(qty_to_assign, 0.0, precision_rounding=rounding)
            return qtyassign_cmp == 0
        uom_obj = self.pool.get('product.uom')
        package_obj = self.pool.get('stock.quant.package')
        quant_obj = self.pool.get('stock.quant')
        link_obj = self.pool.get('stock.move.operation.link')
        quants_in_package_done = set()
        prod2move_ids = {}
        still_to_do = []
        
        moves = sorted([x for x in picking.move_lines if x.state not in ('done', 'cancel')], key=lambda x: (((x.state == 'assigned') and -2 or 0) + (x.partially_available and -1 or 0)))
        for move in moves:
            if not prod2move_ids.get(move.product_id.id):
                prod2move_ids[move.product_id.id] = [{'move': move, 'remaining_qty': move.product_qty}]
            else: