Program: 158874
Project: 158874
Buggy source:
@Override public boolean apply(Game game,Ability source){
  Player controller=game.getPlayer(source.getControllerId());
  MageObject sourceObject=game.getObject(source.getSourceId());
  if (controller == null || sourceObject == null) {
    return false;
  }
  Cards cards=new CardsImpl();
  cards.addAll(controller.getLibrary().getTopCards(game,5));
  controller.revealCards(sourceObject.getName(),cards,game);
  Player opponent;
  Set<UUID> opponents=game.getOpponents(controller.getId());
  if (opponents.size() == 1) {
    opponent=game.getPlayer(opponents.iterator().next());
  }
 else {
    Target target=new TargetOpponent(true);
    controller.chooseTarget(Outcome.Detriment,target,source,game);
    opponent=game.getPlayer(target.getFirstTarget());
  }
  if (opponent != null) {
    TargetCard target=new TargetCard(0,cards.size(),Zone.PICK,new FilterCard("String_Node_Str"));
    List<Card> pile1=new ArrayList<>();
    Cards pile1CardsIds=new CardsImpl();
    target.setRequired(false);
    if (controller.choose(Outcome.Neutral,cards,target,game)) {
      List<UUID> targets=target.getTargets();
      for (      UUID targetId : targets) {
        Card card=game.getCard(targetId);
        if (card != null) {
          pile1.add(card);
          pile1CardsIds.add(card.getId());
        }
      }
    }
    List<Card> pile2=new ArrayList<>();
    Cards pile2CardsIds=new CardsImpl();
    for (    UUID cardId : cards) {
      Card card=game.getCard(cardId);
      if (card != null && !pile1.contains(card)) {
        pile2.add(card);
        pile2CardsIds.add(card.getId());
      }
    }
    boolean choice=opponent.choosePile(Outcome.Detriment,new StringBuilder("String_Node_Str").append(controller.getLogName()).append("String_Node_Str").toString(),pile1,pile2,game);
    Zone pile1Zone=Zone.GRAVEYARD;
    Zone pile2Zone=Zone.HAND;
    if (choice) {
      pile1Zone=Zone.HAND;
      pile2Zone=Zone.GRAVEYARD;
    }
    StringBuilder sb=new StringBuilder(sourceObject.getLogName() + "String_Node_Str").append(pile1Zone.equals(Zone.HAND) ? "String_Node_Str" : "String_Node_Str").append("String_Node_Str");
    int i=0;
    for (    UUID cardUuid : pile1CardsIds) {
      i++;
      Card card=game.getCard(cardUuid);
      if (card != null) {
        sb.append(card.getName());
        if (i < pile1CardsIds.size()) {
          sb.append("String_Node_Str");
        }
        card.moveToZone(pile1Zone,source.getSourceId(),game,false);
      }
    }
    game.informPlayers(sb.toString());
    sb=new StringBuilder(sourceObject.getLogName() + "String_Node_Str").append(pile2Zone.equals(Zone.HAND) ? "String_Node_Str" : "String_Node_Str").append("String_Node_Str");
    i=0;
    for (    UUID cardUuid : pile2CardsIds) {
      Card card=game.getCard(cardUuid);
      if (card != null) {
        i++;
        sb.append("String_Node_Str").append(card.getName());
        if (i < pile2CardsIds.size()) {
          sb.append("String_Node_Str");
        }
        card.moveToZone(pile2Zone,source.getSourceId(),game,false);
      }
    }
    game.informPlayers(sb.toString());
  }
  return true;
}

Fixed version (ground truth):
@Override public boolean apply(Game game,Ability source){
  Player controller=game.getPlayer(source.getControllerId());
  MageObject sourceObject=game.getObject(source.getSourceId());
  if (controller == null || sourceObject == null) {
    return false;
  }
  Cards cards=new CardsImpl();
  cards.addAll(controller.getLibrary().getTopCards(game,5));
  controller.revealCards(sourceObject.getIdName(),cards,game);
  Player opponent;
  Set<UUID> opponents=game.getOpponents(controller.getId());
  if (opponents.size() == 1) {
    opponent=game.getPlayer(opponents.iterator().next());
  }
 else {
    Target target=new TargetOpponent(true);
    controller.chooseTarget(Outcome.Detriment,target,source,game);
    opponent=game.getPlayer(target.getFirstTarget());
  }
  if (opponent != null) {
    TargetCard target=new TargetCard(0,cards.size(),Zone.PICK,new FilterCard("String_Node_Str"));
    List<Card> pile1=new ArrayList<>();
    Cards pile1CardsIds=new CardsImpl();
    target.setRequired(false);
    if (controller.choose(Outcome.Neutral,cards,target,game)) {
      List<UUID> targets=target.getTargets();
      for (      UUID targetId : targets) {
        Card card=game.getCard(targetId);
        if (card != null) {
          pile1.add(card);
          pile1CardsIds.add(card.getId());
        }
      }
    }
    List<Card> pile2=new ArrayList<>();
    Cards pile2CardsIds=new CardsImpl();
    for (    UUID cardId : cards) {
      Card card=game.getCard(cardId);
      if (card != null && !pile1.contains(card)) {
        pile2.add(card);
        pile2CardsIds.add(card.getId());
      }
    }
    boolean choice=opponent.choosePile(Outcome.Detriment,"String_Node_Str" + controller.getName() + "String_Node_Str",pile1,pile2,game);
    Zone pile1Zone=Zone.GRAVEYARD;
    Zone pile2Zone=Zone.HAND;
    if (choice) {
      pile1Zone=Zone.HAND;
      pile2Zone=Zone.GRAVEYARD;
    }
    StringBuilder sb=new StringBuilder(sourceObject.getLogName() + "String_Node_Str").append(pile1Zone.equals(Zone.HAND) ? "String_Node_Str" : "String_Node_Str").append("String_Node_Str");
    int i=0;
    for (    UUID cardUuid : pile1CardsIds) {
      i++;
      Card card=game.getCard(cardUuid);
      if (card != null) {
        sb.append(GameLog.getColoredObjectName(card));
        if (i < pile1CardsIds.size()) {
          sb.append("String_Node_Str");
        }
        card.moveToZone(pile1Zone,source.getSourceId(),game,false);
      }
    }
    game.informPlayers(sb.toString());
    sb=new StringBuilder(sourceObject.getLogName() + "String_Node_Str").append(pile2Zone.equals(Zone.HAND) ? "String_Node_Str" : "String_Node_Str").append("String_Node_Str");
    i=0;
    for (    UUID cardUuid : pile2CardsIds) {
      Card card=game.getCard(cardUuid);
      if (card != null) {
        i++;
        sb.append("String_Node_Str").append(GameLog.getColoredObjectName(card));
        if (i < pile2CardsIds.size()) {
          sb.append("String_Node_Str");
        }
        card.moveToZone(pile2Zone,source.getSourceId(),game,false);
      }
    }
    game.informPlayers(sb.toString());
  }
  return true;
}