Program: 158120
Project: 158120
Buggy source:
@Override public boolean apply(Game game,Ability source){
  StackObject stackObject=game.getStack().getStackObject(source.getFirstTarget());
  MageObject sourceObject=game.getObject(source.getSourceId());
  if (stackObject != null && sourceObject != null) {
    Targets targets=new Targets();
    Ability sourceAbility;
    String oldTargetName=null;
    if (stackObject instanceof Spell) {
      Spell spell=(Spell)stackObject;
      sourceAbility=spell.getSpellAbility();
    }
 else     if (stackObject instanceof StackAbility) {
      StackAbility stackAbility=(StackAbility)stackObject;
      sourceAbility=stackAbility;
    }
 else {
      return false;
    }
    for (    UUID modeId : sourceAbility.getModes().getSelectedModes()) {
      Mode mode=sourceAbility.getModes().get(modeId);
      targets.addAll(mode.getTargets());
    }
    boolean twoTimesTarget=false;
    if (targets.size() == 1 && targets.get(0).getTargets().size() == 1) {
      Target target=targets.get(0);
      if (target.getFirstTarget().equals(source.getSourceId())) {
        return true;
      }
      if (target.canTarget(stackObject.getControllerId(),source.getSourceId(),sourceAbility,game)) {
        oldTargetName=getTargetName(targets.getFirstTarget(),game);
        target.clearChosen();
        target.addTarget(source.getSourceId(),stackObject.getStackAbility(),game);
      }
    }
 else {
      Player controller=game.getPlayer(source.getControllerId());
      boolean validTargets=false;
      do {
        for (        Target target : targets) {
          for (          UUID targetId : target.getTargets()) {
            String name=getTargetName(targetId,game);
            if (targetId.equals(source.getSourceId()) || target.getTargets().contains(source.getSourceId())) {
              twoTimesTarget=true;
              continue;
            }
            if (target.canTarget(stackObject.getControllerId(),source.getSourceId(),sourceAbility,game) && !twoTimesTarget) {
              validTargets=true;
              if (name != null && controller.chooseUse(Outcome.Neutral,"String_Node_Str" + name + "String_Node_Str"+ sourceObject.getLogName()+ '?',source,game)) {
                oldTargetName=getTargetName(targetId,game);
                int damageAmount=target.getTargetAmount(targetId);
                target.remove(targetId);
                target.addTarget(source.getSourceId(),stackObject.getStackAbility(),game);
                target.setTargetAmount(source.getSourceId(),damageAmount,game);
                break;
              }
            }
          }
          if (oldTargetName != null) {
            break;
          }
        }
        if (oldTargetName == null) {
          game.informPlayer(controller,"String_Node_Str" + sourceObject.getIdName() + '!');
        }
      }
 while (validTargets && oldTargetName == null);
    }
    if (oldTargetName != null) {
      game.informPlayers(sourceObject.getLogName() + "String_Node_Str" + stackObject.getLogName()+ "String_Node_Str"+ oldTargetName+ "String_Node_Str"+ sourceObject.getLogName());
    }
 else     if (twoTimesTarget) {
      game.informPlayers(sourceObject.getLogName() + "String_Node_Str" + sourceObject.getLogName()+ "String_Node_Str"+ stackObject.getLogName());
    }
 else {
      game.informPlayers(sourceObject.getLogName() + "String_Node_Str" + sourceObject.getLogName()+ "String_Node_Str"+ stackObject.getLogName());
    }
    return true;
  }
  return false;
}

Fixed version (ground truth):
@Override public boolean apply(Game game,Ability source){
  StackObject stackObject=game.getStack().getStackObject(source.getFirstTarget());
  MageObject sourceObject=game.getObject(source.getSourceId());
  if (stackObject != null && sourceObject != null) {
    Targets targets=new Targets();
    Ability sourceAbility;
    String oldTargetName=null;
    if (stackObject instanceof Spell) {
      Spell spell=(Spell)stackObject;
      sourceAbility=spell.getSpellAbility();
    }
 else     if (stackObject instanceof StackAbility) {
      StackAbility stackAbility=(StackAbility)stackObject;
      sourceAbility=stackAbility;
    }
 else {
      return false;
    }
    for (    UUID modeId : sourceAbility.getModes().getSelectedModes()) {
      Mode mode=sourceAbility.getModes().get(modeId);
      targets.addAll(mode.getTargets());
    }
    boolean twoTimesTarget=false;
    if (targets.size() == 1 && targets.get(0).getTargets().size() == 1) {
      Target target=targets.get(0);
      if (target.getFirstTarget().equals(source.getSourceId())) {
        return true;
      }
      if (target.canTarget(stackObject.getControllerId(),source.getSourceId(),sourceAbility,game)) {
        oldTargetName=getTargetName(targets.getFirstTarget(),game);
        target.clearChosen();
        target.addTarget(source.getSourceId(),stackObject.getStackAbility(),game);
      }
    }
 else {
      Player controller=game.getPlayer(source.getControllerId());
      boolean validTargets=false;
      do {
        for (        Target target : targets) {
          if (target.getTargets().contains(source.getSourceId())) {
            continue;
          }
          for (          UUID targetId : target.getTargets()) {
            String name=getTargetName(targetId,game);
            if (target.canTarget(stackObject.getControllerId(),source.getSourceId(),sourceAbility,game)) {
              validTargets=true;
              if (name != null && controller.chooseUse(Outcome.Neutral,"String_Node_Str" + name + "String_Node_Str"+ sourceObject.getLogName()+ '?',source,game)) {
                oldTargetName=getTargetName(targetId,game);
                int damageAmount=target.getTargetAmount(targetId);
                target.remove(targetId);
                target.addTarget(source.getSourceId(),stackObject.getStackAbility(),game);
                target.setTargetAmount(source.getSourceId(),damageAmount,game);
                break;
              }
            }
          }
          if (oldTargetName != null) {
            break;
          }
        }
        if (oldTargetName == null) {
          game.informPlayer(controller,"String_Node_Str" + sourceObject.getIdName() + '!');
        }
      }
 while (validTargets && oldTargetName == null);
    }
    if (oldTargetName != null) {
      game.informPlayers(sourceObject.getLogName() + "String_Node_Str" + stackObject.getLogName()+ "String_Node_Str"+ oldTargetName+ "String_Node_Str"+ sourceObject.getLogName());
    }
 else     if (twoTimesTarget) {
      game.informPlayers(sourceObject.getLogName() + "String_Node_Str" + sourceObject.getLogName()+ "String_Node_Str"+ stackObject.getLogName());
    }
 else {
      game.informPlayers(sourceObject.getLogName() + "String_Node_Str" + sourceObject.getLogName()+ "String_Node_Str"+ stackObject.getLogName());
    }
    return true;
  }
  return false;
}