message: Update outdated comment about updating MirroredVariables.
diff: @@ -1020,7 +1020,8 @@ class MirroredVariable(DistributedVariable, Mirrored):
  # TODO(b/154017756): Make _dense_var_to_tensor consistent between ON_READ
  # and ON_WRITE.
  # Try to avoid assignments to and other mutations of MirroredVariable
  - # state except through a DistributionStrategy.extended.update() call.
  + # state except through a DistributionStrategy.extended.update() or any of
  + # the `assign*` and `scatter*` calls.
  if as_ref:
  # A TF 1.x case where the variable is a boolean variable and used like:
  # tf.cond(v, true_fn, false_fn).
  