message: Prevent redundant ":0" in summary names
  Take identical approach as is done with thresholds: using tf.Variable.op.name instead of tf.Variable.name, to prevent TensorFlow saying summary names are illegal (due to ":")
diff: @@ -520,7 +520,7 @@ class Pruning(object):
  thresholds = get_thresholds()
  for index, mask in enumerate(masks):
  if not self._exists_in_do_not_prune_list(mask.name):
  - summary.scalar(mask.name + '/sparsity', nn_impl.zero_fraction(mask))
  + summary.scalar(mask.op.name + '/sparsity', nn_impl.zero_fraction(mask))
  summary.scalar(thresholds[index].op.name + '/threshold',
  thresholds[index])
  