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._action_done()
        quant = self.env['stock.quant']._gather(self.product3, self.stock_location)
        self.assertEqual(len(quant), 1.0)
        self.assertNotEqual(quant.in_date, False)
        
        initial_incoming_date = quant.in_date
        move2 = self.env['stock.move'].create({
            'name': 'test_in_date_1',
            'location_id': self.stock_location.id,
            'location_dest_id': self.pack_location.id,
            'product_id': self.product3.id,
            'product_uom': self.uom_unit.id,
            'product_uom_qty': 1.0,
        })
        move2._action_confirm()
        move2._action_assign()
        move2.move_line_ids.qty_done = 1
        move2._action_done()
        quant = self.env['stock.quant']._gather(self.product3, self.pack_location)
        self.assertEqual(len(quant), 1.0)
        self.assertEqual(quant.in_date, initial_incoming_date)
    def test_in_date_2(self):
        """ Check that editing a done move line for a tracked product and changing its lot
        correctly restores the original lot with its incoming date and remove the new lot
        with its incoming date.
        """
        lot1 = self.env['stock.production.lot'].create({
            'name': 'lot1',
            'product_id': self.product3.id,
        })