Migration to 4.8 fails because of duplicated button
There is a button, that is created with stock.xml and id of that button was changed in #6389 (closed), so if this module (stock_package_shipping) was installed in 4.6 there is a button with the same name but different id in database. So migration fails with the following error:
In tag record: model ir.model.button with id shipment_out_create_shipping_button.
...
UserError: The button name in model must be unique! -