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 


product = self.product_id.with_context(lang=self.partner_id.lang or self.env.user.lang)
        self.name = product.partner_ref
        self.product_uom = product.uom_id.id
        return {'domain': {'product_uom': [('category_id', '=', product.uom_id.category_id.id)]}}
    @api.onchange('date_expected')
    def onchange_date(self):
        if self.date_expected:
            self.date = self.date_expected
    @api.onchange('product_uom')
    def onchange_product_uom(self):
        if self.product_uom.factor > self.product_id.uom_id.factor:
            return {
                'warning': {
                    'title': "Unsafe unit of measure",
                    'message': _("You are using a unit of measure smaller than the one you are using in "
                                 "order to stock your product. This can lead to rounding problem on reserved quantity! "
                                 "You should use the smaller unit of measure possible in order to valuate your stock or "
                                 "change its rounding precision to a smaller value (example: 0.00001)."),
                }
            }
    def _assign_picking(self):