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.assertEqual(self.env['stock.quant']._get_available_quantity(self.product2, self.stock_location), 2.0)
        
        move1 = self.env['stock.move'].create({
            'name': 'test_in_1',
            'location_id': self.stock_location.id,
            'location_dest_id': self.customer_location.id,
            'product_id': self.product2.id,
            'product_uom': self.uom_unit.id,
            'product_uom_qty': 2.0,
        })
        move1._action_confirm()
        move1._action_assign()
        move1.move_line_ids.write({'qty_done': 1.0})
        move1._action_done()
        self.env['stock.quant']._update_available_quantity(self.product2, self.stock_location, 2)
        lot3 = self.env['stock.production.lot'].create({
            'name': 'lot3',
            'product_id': self.product2.id,
        })
        lot4 = self.env['stock.production.lot'].create({
            'name': 'lot4',
            'product_id': self.product2.id,
        })
        self.env['stock.move.line'].create({
            'move_id': move1.id,
            'product_id': move1.product_id.id,
            'qty_done': 1,
            'product_uom_id': move1.product_uom.id,
            'location_id': move1.location_id.id,
            'location_dest_id': move1.location_dest_id.id,