message: Cope with ShapedBuffers which are Tuples
diff: @@ -85,7 +85,6 @@ StatusOr<std::unique_ptr<ShapedBuffer>> PoplarExecutable::ExecuteOnStream(
  std::vector<se::DeviceMemoryBase> argument_buffers;
  for (int i = 0; i < arguments.size(); ++i) {
  - TF_RET_CHECK(!ShapeUtil::IsTuple(arguments[i]->shape()));
  argument_buffers.push_back(arguments[i]->buffer(/*index=*/{}));
  }
  