token_formatters.py

    def validate_token(self, token):
        """Validates a Fernet token and returns the payload attributes."""
        # Convert v2 unicode token to a string
        if not isinstance(token, six.binary_type):
            token = token.encode('ascii')

#to    
    
    def validate_token(self, token):
        """Validates a Fernet token and returns the payload attributes."""
        # Convert v2 unicode token to a string
        if isinstance(token, six.text_type):
            token = token.encode('ascii')
        if not isinstance(token, six.binary_type):
            raise exception.ValidationError(_('This is not a recognized Fernet token'))

For https://review.openstack.org/#/c/206921/