Impacted versions: 9.0

Steps to reproduce:

* Create an MTO product with 
  * Product Type: Stockable Product
  * Routes: "Buy" and "Make to Order"
* Update Qty on Hand to any quantity (i.e, 2).
* Create a sales order with this product and a number <= to the one in the step before.
* Confirm the sales order.

Current behavior:

The created delivery picking appears in state "Reserved" and the current quantity on stock has been reserved, allowing you to transfer that stock.

Expected behavior:

The created delivery picking should be in "Waiting another operation", or at least in "Waiting availability" until the purchase order is confirmed (if you have defined a supplier for the product and the procurement creates the purchase order), which seems to be the current behavior when there's no stock available (is this also correct, as it allows to manually reserve?).
""" On change of product id, if finds UoM, quantity
        @param prod_id: Changed Product id
        @param loc_id: Source location id
        @param loc_dest_id: Destination location id
        @param partner_id: Address id of partner
        @return: Dictionary of values
        """
        if not prod_id:
            return {'domain': {'product_uom': []}}
        user = self.pool.get('res.users').browse(cr, uid, uid)
        lang = user and user.lang or False
        if partner_id:
            addr_rec = self.pool.get('res.partner').browse(cr, uid, partner_id)
            if addr_rec:
                lang = addr_rec and addr_rec.lang or False
        ctx = {'lang': lang}