message: Proper check for eagerness in concat_grad
diff: @@ -107,7 +107,7 @@ def _ConcatGradHelper(op, grad, start_value_index, end_value_index, dim_index):
  out_grads = []
  if isinstance(grad, ops.Tensor):
  - if context.executing_eagerly():
  + if context.executing_eagerly() or isinstance(concat_dim, ops.EagerTensor):
  # Using mod here for convenience since concat_dim is already verified
  # in concat implementation to be within the allowed [-rank, rank) range.
  non_neg_concat_dim = (
  