message: Uses dynamic shapes for IndexedSlices aggregation.
  Fixes
diff: @@ -568,8 +568,8 @@ def _aggregate_grads(gradients):
  if isinstance(grad, ops.Tensor):
  indexed_slices = ops.IndexedSlices(
  grad,
  - math_ops.range(grad.shape[0]),
  - constant_op.constant(grad.shape.as_list()))
  + math_ops.range(array_ops.shape(grad)[0]),
  + array_ops.shape(grad))
  indexed_slices_list.append(indexed_slices)
  else:
  indexed_slices_list.append(grad)
  