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 


""" In a picking with two moves, one partially available and one unavailable, clicking
        on validate without filling any quantities should open a wizard asking to process all the
        reservation (so, only a part of one of the moves). Validating this wizard should open
        another one asking for the creation of a backorder. If the backorder is created, it should
        contain the quantities not processed.
        """
        product5 = self.env['product.product'].create({
            'name': 'Product 5',
            'type': 'product',
            'categ_id': self.env.ref('product.product_category_all').id,
        })
        self.env['stock.quant']._update_available_quantity(self.product1, self.stock_location, 1)
        picking = self.env['stock.picking'].create({
            'location_id': self.stock_location.id,
            'location_dest_id': self.pack_location.id,
            'picking_type_id': self.env.ref('stock.picking_type_internal').id,
        })
        product1_move = self.env['stock.move'].create({
            'name': 'product1_move',
            'location_id': self.stock_location.id,
            'location_dest_id': self.pack_location.id,
            'picking_id': picking.id,
            'product_id': self.product1.id,
            'product_uom': self.uom_unit.id,
            'product_uom_qty': 100,
        })
        product5_move = self.env['stock.move'].create({
            'name': 'product3_move',