message: Match MSC behaviour for threads when disabled (thread-aware mode)
diff: @@ -152,8 +152,17 @@ export function makeReplyMixIn(ev?: MatrixEvent): IEventRelation {
  },
  };
  - if (SettingsStore.getValue("feature_thread") && ev.threadRootId) {
  + if (ev.threadRootId) {
  + if (SettingsStore.getValue("feature_thread")) {
  mixin.is_falling_back = false;
  + } else {
  + // Clients that do not offer a threading UI should behave as follows when replying, for best interaction
  + // with those that do. They should set the m.in_reply_to part as usual, and then add on
  + // "rel_type": "m.thread" and "event_id": "$thread_root", copying $thread_root from the replied-to event.
  + const relation = ev.getRelation();
  + mixin.rel_type = relation.rel_type;
  + mixin.event_id = relation.event_id;
  + }
  }
  return mixin;
  