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
move1.quantity_done = 1
        
        move1.write({'move_line_ids': [(0, 0, {
            'product_id': self.product1.id,
            'product_uom_id': self.uom_unit.id,
            'qty_done': 2,
            'product_uom_qty': 0,
            'lot_id': False,
            'package_id': False,
            'result_package_id': False,
            'location_id': move1.location_id.id,
            'location_dest_id': move1.location_dest_id.id,
        })]})
        move1._action_done()
        self.assertEqual(self.env['stock.quant']._get_available_quantity(self.product1, self.customer_location), 3.0)
    def test_edit_reserved_move_line_1(self):
        """ Test that editing a stock move line linked to an untracked product correctly and
        directly adapts the reservation. In this case, we edit the sublocation where we take the
        product to another sublocation where a product is available.
        """
        shelf1_location = self.env['stock.location'].create({
            'name': 'shelf1',
            'usage': 'internal',
            'location_id': self.stock_location.id,
        })
        shelf2_location = self.env['stock.location'].create({
            'name': 'shelf1',
            'usage': 'internal',
            'location_id': self.stock_location.id,
        })