message: RemoveTrivialPassthroughOp was violating the graph invariant of no unused arrays.
diff: @@ -57,6 +57,12 @@ void Reroute(const string& from, const string& to, Model* model) {
  to_array.final_data_type == ArrayDataType::kNone) {
  to_array.final_data_type = from_array.final_data_type;
  }
  + // The 'from' array may now be unused. We delete it here immediately
  + // so that this function doesn't violate graph invariants (no unused arrays)
  + // and as it's not trivial to get this right for the caller since
  + // DeleteOpAndArrays will no longer delete this array, since it's no longer
  + // referenced by this op.
  + DeleteArrayIfUnused(from, model);
  }
  } // namespace
  