**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.


lang = addr_rec and addr_rec.lang or False
        ctx = {'lang': lang}
        product = self.pool.get('product.product').browse(cr, uid, [prod_id], context=ctx)[0]
        uos_id = product.uos_id and product.uos_id.id or False
        result = {
            'name': product.partner_ref,
            'product_uom': product.uom_id.id,
            'product_uos': uos_id,
            'product_uom_qty': 1.00,
            'product_uos_qty': self.pool.get('stock.move').onchange_quantity(cr, uid, ids, prod_id, 1.00, product.uom_id.id, uos_id)['value']['product_uos_qty'],
        }
        if loc_id:
            result['location_id'] = loc_id
        if loc_dest_id:
            result['location_dest_id'] = loc_dest_id
        return {'value': result}
    def _prepare_picking_assign(self, cr, uid, move, context=None):
        """ Prepares a new picking for this move as it could not be assigned to
        another picking. This method is designed to be inherited.
        """
        values = {
            'origin': move.origin,
            'company_id': move.company_id and move.company_id.id or False,
            'move_type': move.group_id and move.group_id.move_type or 'direct',
            'partner_id': move.partner_id.id or False,
            'picking_type_id': move.picking_type_id and move.picking_type_id.id or False,
            }
        return values
    @api.cr_uid_ids_context
    def _picking_assign(self, cr, uid, move_ids, procurement_group, location_from, location_to, context=None):