It appears that IntegerProperty._validate() is not taking "long" into account under Python 2:

This is different from previous behaviour: https://github.com/GoogleCloudPlatform/datastore-ndb-python/blob/8f0895e5a01aa4387c01fec1d2644d5a084961eb/ndb/model.py#L1617

  def _validate(self, value):
    if not isinstance(value, (int, long)):
      raise datastore_errors.BadValueError('Expected integer, got %r' %
                                           (value,))
    return int(value)

The new implementation should probably be using six.integer_types.

This is blocking our migration for https://github.com/google/clusterfuzz, so it would be great it this could be fixed and released.

Thanks!