v1new ReadFromDatastore returns duplicates if keys are of mixed types

// code placeholder
from __future__ import unicode_literals
import apache_beam as beam
from apache_beam.io.gcp.datastore.v1new.types import Key, Entity, Query
from apache_beam.io.gcp.datastore.v1new import datastoreio


config = dict(project='your-google-project', namespace='test')


def test_mixed():
    keys = [
        Key(['mixed', '10038260-iperm_eservice'], **config),
        Key(['mixed', 4812224868188160], **config),
        Key(['mixed', '99152975-pointshop'], **config)
    ]

    entities = map(lambda key: Entity(key=key), keys)

    with beam.Pipeline() as p:
        (p
            | beam.Create(entities)
            | datastoreio.WriteToDatastore(project=config['project'])
        )

    query = Query(kind='mixed', **config)

    with beam.Pipeline() as p:
        (p
            | datastoreio.ReadFromDatastore(query=query, num_splits=4)
            | beam.io.WriteToText('tmp.txt', num_shards=1, shard_name_template='')
    )

    items = open('tmp.txt').read().strip().split('\n')
    assert len(items) == 3, 'incorrect number of items'