Datastore Enum Types No Longer Serialized

[Larry Schiefer]

We are using GAE python standard environment (Python 2.7) and suddenly our app started experiencing issues when serializing a datastore enum property. Our code has been deployed and working for over 6 months and today it is failing. For example:

class SomeType(messages.Enum):

    FIRST_TYPE = 1

    SECOND_TYPE = 2

    THIRD_TYPE = 3

class SomeEntity(polymodel.PolyModel):

    # Other fields not shown

    something = msgprop.EnumProperty(SomeType, repeated=true)

    def get_msg_data(self):

        msg_data = {

            'something': json.dumps(self.something)
        }

        return msg_data

The call to json.dumps above started failing in our instance today with an error like this:

TypeError: SomeType(FIRST_TYPE, 1) is not JSON serializable

Is anyone else seeing this? Note that using the same enum type within a message where we are not calling json.dumps directly works fine.