message: Small change in tf.nn.sufficient_statistics to guard against unknown shapes.
  Use is_fully_defined instead of checking shape.dims[d] as the dims variable may be None, if the rank is unknown.
diff: @@ -842,7 +842,8 @@ def sufficient_statistics(x, axes, shift=None, keep_dims=None, name=None,
  with ops.name_scope(name, "sufficient_statistics", [x, shift]):
  x = ops.convert_to_tensor(x, name="x")
  x_shape = x.get_shape()
  - if all(x_shape.dims[d].value is not None for d in axes):
  + if x_shape.rank is not None and all(
  + x_shape.dims[d].value is not None for d in axes):
  counts = 1
  for d in axes:
  counts *= x_shape.dims[d].value
  