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?).
addons/stock/stock.py
context = context or {}
        for move in self.browse(cr, uid, ids, context=context):
            if move.state not in ('draft', 'cancel'):
                raise UserError(_('You can only delete draft moves.'))
        return super(stock_move, self).unlink(cr, uid, ids, context=context)
    def action_scrap(self, cr, uid, ids, quantity, location_id, restrict_lot_id=False, restrict_partner_id=False, context=None):
        """ Move the scrap/damaged product into scrap location
        @param cr: the database cursor
        @param uid: the user id
        @param ids: ids of stock move object to be scrapped
        @param quantity : specify scrap qty
        @param location_id : specify scrap location
        @param context: context arguments
        @return: Scraped lines
        """
        quant_obj = self.pool.get("stock.quant")
        
        if quantity <= 0:
            raise UserError(_('Please provide a positive quantity to scrap.'))
        res = []
        for move in self.browse(cr, uid, ids, context=context):
            source_location = move.location_id
            if move.state == 'done':
                source_location = move.location_dest_id
            
            
                
                
            move_qty = move.product_qty