Record is considered as modified after creating it using a button

Steps to reproduce:

1. Create a new purchase record
2. Set its party and click the cancel button

Current behaviour:

• The save button is enabled and the new button is disabled. Users needs to click the reload button to create a new record

Expected behaviour:

• The save button is no longer enabled as the record is already saved by using the button and the new button is enabled to create a new button.

Found on 7.0 series using both sao and tryton