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
self.env['stock.quant'].create({
            'product_id': self.product1.id,
            'location_id': self.stock_location.id,
            'quantity': 2,
        })
        self.assertEqual(len(self.env['stock.quant']._gather(self.product1, self.stock_location)), 2)
        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product1, self.stock_location), 5)
        
        move1 = self.env['stock.move'].create({
            'name': 'test_unreserve_5',
            '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': 5.0,
        })
        self.assertEqual(move1.state, 'draft')
        
        move1._action_confirm()
        self.assertEqual(move1.state, 'confirmed')
        
        move1._action_assign()
        self.assertEqual(move1.state, 'assigned')
        self.assertEqual(len(move1.move_line_ids), 1)
        move1._do_unreserve()
        quants = self.env['stock.quant']._gather(self.product1, self.stock_location)
        self.assertEqual(len(quants), 2.0)
        for quant in quants:
            self.assertEqual(quant.reserved_quantity, 0)
    def test_unreserve_6(self):