message: Small change to how damping constants get transformed.  Switched from using tf.square to **0.5. This will preserve them as floats if they are already, so the dictionaries work properly.  See b/62785471
diff: @@ -468,8 +468,8 @@ class KroneckerProductFB(FisherBlock):
  pi = utils.compute_pi(self._input_factor.get_cov(),
  self._output_factor.get_cov())
  - self._input_damping = math_ops.sqrt(damping) * pi
  - self._output_damping = math_ops.sqrt(damping) / pi
  + self._input_damping = (damping**0.5) * pi
  + self._output_damping = (damping**0.5) / pi
  self._input_factor.register_damped_inverse(self._input_damping)
  self._output_factor.register_damped_inverse(self._output_damping)
  