title: Odoo 10 - Default value for field based on condition
body: <p>I am extending stock.picking to modify the default value used as <code>location_dest_id</code>.</p>
  
  <p>Standard definition is:</p>
  
  <pre><code>location_dest_id = fields.Many2one(¬
      'stock.location', "Destination Location Zone",¬
      default=lambda self: self.env['stock.picking.type'].browse(self._context.get('default_picking_type_id')).default_location_dest_id,¬
      readonly=True, required=True,¬
      states={'draft': [('readonly', False)]})¬
  </code></pre>
  
  <p>Which basically uses the default location defined in the picking_type.</p>
  
  <p>I have extended the model so there is a new field in <code>picking_type</code> named <code>force_destination</code>. I would like to set the destination on the stock.picking based on that condition.</p>
  
  <p>Pseudocode:</p>
  
  <pre><code>location_dest_id = fields.Many2one(¬
  ....
      default=
          if self.env['stock.picking.type'].browse(self._context.get('default_picking_type_id')).force_destination:
              default=1
          else:
              default=lambda self: self.env['stock.picking.type'].browse(self._context.get('default_picking_type_id')).default_location_dest_id
  
  ....
  </code></pre>