Migrated issue, originally created by Mario Benito Ríos (@Maberi)

With MySQL backend, on commit after creating a new object with "autoincrement" PK, key updating is triggering validator. See https://bitbucket.org/zzzeek/sqlalchemy/src/2de7f94739ec1873e1dce48797e1e6f12044cf4c/lib/sqlalchemy/orm/persistence.py?at=master#cl-650

Documentation says only user assignments trigger validations, so this case shouldn't trigger validation.