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 


addons/stock/tests/test_move.py
'location_dest_id': self.pack_location.id,
            'product_id': self.product2.id,
            'product_uom': uom_3units.id,
            'product_uom_qty': 1.0,
            'picking_id': picking_stock_pack.id,
        })
        picking_pack_cust = self.env['stock.picking'].create({
            'location_id': self.pack_location.id,
            'location_dest_id': self.customer_location.id,
            'picking_type_id': self.env.ref('stock.picking_type_out').id,
        })
        move_pack_cust = self.env['stock.move'].create({
            'name': 'test_link_assign_0',
            'location_id': self.pack_location.id,
            'location_dest_id': self.customer_location.id,
            'product_id': self.product2.id,
            'product_uom': uom_3units.id,
            'product_uom_qty': 1.0,
            'picking_id': picking_pack_cust.id,
        })
        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()
        picking_stock_pack.action_assign()
        for ml in picking_stock_pack.move_lines.move_line_ids:
            ml.qty_done = 1
        picking_stock_pack.button_validate()
        self.assertEqual(picking_pack_cust.state, 'assigned')
        for ml in picking_pack_cust.move_lines.move_line_ids:
            if ml.lot_id.name != 'lot3':