See this version of systemDictionary.cpp

http://hg.openjdk.java.net/jdk9/jdk9/hotspot/file/ee069fd4b66b/src/share/vm/classfile/systemDictionary.cpp#l1220

instanceKlassHandle SystemDictionary::load_shared_class(instanceKlassHandle ik,
                                                        Handle class_loader,
                                                        Handle protection_domain, TRAPS) {
  if (ik.not_null()) {
    instanceKlassHandle nh = instanceKlassHandle(); // null Handle
    Symbol* class_name = ik->name();

    // Found the class, now load the superclass and interfaces. If they
    // are shared, add them to the main system dictionary and reset
    // their hierarchy references (supers, subs, and interfaces).

    if (ik->super() != NULL) {
      Symbol* cn = ik->super()->name();
      Klass *s = resolve_super_or_fail(class_name, cn,
                                       class_loader, protection_domain, true, CHECK_(nh));
      if (s != ik->super()) {
        // The dynamically resolved super class is not the same as the one we used during dump time,
        // so we cannot use ik.
        return nh;
      }
    }

    Array<Klass*>* interfaces = ik->local_interfaces();
    int num_interfaces = interfaces->length();
    for (int index = 0; index < num_interfaces; index++) {
      Klass* k = interfaces->at(index);

      // Note: can not use InstanceKlass::cast here because
      // interfaces' InstanceKlass's C++ vtbls haven't been
      // reinitialized yet (they will be once the interface classes
      // are loaded)
      Symbol* name = k->name();
      Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_(nh));
      if (k != i) {
        // The dynamically resolved interface class is not the same as the one we used during dump time,
        // so we cannot use ik.
        return nh;
      }
    }

The "// Found the class ..." comment is wrong and unclear. There is no "resetting their hierarchy references" happening here.