message: [TF:XLA] Do not filter backedge in DFS traversal in cluster_scoping.
  Do not filter any edges when traversing to find out all of the transitive
  successor closure.  This should better serve the current needs to preserve the
  pipeline stages by separating the transitive predecessors of Stage and
  transitive successors of Unstage whenever possible.
diff: @@ -96,12 +96,12 @@ void ClusterScopingPassImpl::AddScopeToAllTransitiveSuccessors(Node* start) {
  std::vector<Node*> starts;
  starts.push_back(start);
  auto enter = [&](Node* n) { AddOrAppendXlaInternalScope(n, unique_suffix); };
  - auto not_back_edge = [](const Edge& edge) -> bool {
  - return !edge.src()->IsNextIteration();
  - };
  DFSFrom(*graph_, starts, enter, /*leave=*/nullptr,
  /*stable_comparator=*/NodeComparatorName(),
  - /*edge_filter=*/not_back_edge);
  + // Do not filter any edges to better capture the semantics of
  + // transitive closure of successors. We may revisit this when
  + // we see more cases needing cluster scoping in the future.
  + /*edge_filter=*/nullptr);
  }
  // This preserves the parallelism between pipeline stages. For example, below
  