message: MAINT: Fix unused mut warning
diff: @@ -231,9 +231,9 @@ fn simple_fast_post_order<G>(graph: G,
  post_order.push(node);
  for successor in graph.neighbors(node) {
  - let mut predecessors = predecessor_sets.entry(successor)
  - .or_insert_with(HashSet::new);
  - predecessors.insert(node);
  + predecessor_sets.entry(successor)
  + .or_insert_with(HashSet::new)
  + .insert(node);
  }
  }
  