Comment 1 for bug 1180832

added:

class stock_inventory(osv.osv):

    _inherit = 'stock.inventory'

    def _inventory_line_hook(self, cr, uid, inventory_line, move_vals):
        """
        Added to transfer pieces_qty to stock_move
        """
        if inventory_line.pieces_qty:
            move_vals.update({'pieces_qty':inventory_line.pieces_qty})
        return super(stock_inventory, self)._inventory_line_hook(cr, uid, inventory_line, move_vals)

stock_inventory()

to tcv_stock driver