Impacted versions:
11.0

I don't know if it is an issue, but I think is strange.

`product_qty` is in unit of `product` : https://github.com/odoo/odoo/blob/11.0/addons/stock/models/stock_move.py#L240
`reserved_availability` is in unit of `stock.move` : https://github.com/odoo/odoo/blob/11.0/addons/stock/models/stock_move.py#L295

`move.product_qty - move.reserved_availability` seems to have no sens, no ?

https://github.com/odoo/odoo/blob/11.0/addons/stock/models/stock_move.py#L915
https://github.com/odoo/odoo/blob/11.0/addons/stock/models/stock_move.py#L917
https://github.com/odoo/odoo/blob/11.0/addons/stock/models/stock_move.py#L924

thank for your answer

@jco-odoo 
@alnslang 


})
        move_stock_pack.write({'move_dest_ids': [(4, move_pack_cust.id, 0)]})
        move_pack_cust.write({'move_orig_ids': [(4, move_stock_pack.id, 0)]})
        (move_stock_pack + move_pack_cust)._action_confirm()
        move_stock_pack._action_assign()
        move_stock_pack.move_line_ids[0].qty_done = 1.0
        move_stock_pack._action_done()
        self.assertEqual(len(move_pack_cust.move_line_ids), 1)
        move_line = move_pack_cust.move_line_ids[0]
        self.assertEqual(move_line.location_id.id, self.pack_location.id)
        self.assertEqual(move_line.location_dest_id.id, self.customer_location.id)
        self.assertEqual(move_pack_cust.state, 'assigned')
    def test_link_assign_2(self):
        """ Test the assignment mechanism when two chained stock moves try to move one unit of a
        tracked product.
        """
        lot1 = self.env['stock.production.lot'].create({
            'name': 'lot1',
            'product_id': self.product1.id,
        })
        
        self.env['stock.quant']._update_available_quantity(self.product1, self.stock_location, 1.0, lot_id=lot1)
        self.assertEqual(len(self.env['stock.quant']._gather(self.product1, self.stock_location, lot1)), 1.0)
        move_stock_pack = self.env['stock.move'].create({
            'name': 'test_link_2_1',
            'location_id': self.stock_location.id,
            'location_dest_id': self.pack_location.id,
            'product_id': self.product1.id,
            'product_uom': self.uom_unit.id,
            'product_uom_qty': 1.0,