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_id': self.stock_location.id,
            'location_dest_id': self.customer_location.id,
            'picking_type_id': self.env.ref('stock.picking_type_out').id,
        })
        move1 = self.env['stock.move'].create({
            'name': 'test_transit_1',
            'location_id': self.stock_location.id,
            'location_dest_id': self.customer_location.id,
            'product_id': self.product1.id,
            'product_uom': self.uom_unit.id,
            'product_uom_qty': 2.0,
            'picking_id': picking.id,
        })
        picking.action_confirm()
        picking.action_assign()
        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product1, self.stock_location), 0)
        move1.quantity_done = 1
        picking.put_in_pack()
        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product1, self.stock_location), 0)
        self.assertEqual(len(picking.move_line_ids), 2)
        unpacked_ml = picking.move_line_ids.filtered(lambda ml: not ml.result_package_id)
        self.assertEqual(unpacked_ml.product_qty, 1)
        unpacked_ml.qty_done = 1
        picking.put_in_pack()
        self.assertEqual(len(picking.move_line_ids), 2)
        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product1, self.stock_location), 0)
        picking.button_validate()
        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product1, self.stock_location), 0)
        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product1, self.customer_location), 2)