Integer max values are not being properly validated in oslo.config

The following option declaration is not being validated at all:

    cfg.Opt('max_password_length',
            type=cfg.types.Integer(max=passlib.utils.MAX_PASSWORD_SIZE),
            default=4096,
            help='Maximum supported length for user passwords; '
                      'decrease to improve performance.'),

This is because the ValueError is returned instead of being raised. The calling code doesn't realize that a validation error occurred.

Accessing identity.max_password_length should cause an exception to be raised.