Program: 159779
Project: 159779
Buggy source:
/** 
 * 800.4a When a player leaves the game, all objects (see rule 109) owned by that player leave  the game and any effects which give that player control of any objects or players end. Then,  if that player controlled any objects on the stack not represented by cards, those objects  cease to exist. Then, if there are any objects still controlled by that player, those objects are exiled. This is not a state-based action. It happens as soon as the player leaves the game. If the player who left the game had priority at the time he or she left, priority passes to the next player in turn order who's still in the game. #
 * @param playerId 
 */
@Override public void leave(UUID playerId){
  Player player=getPlayer(playerId);
  player.leave();
  for (Iterator<Permanent> it=getBattlefield().getAllPermanents().iterator(); it.hasNext(); ) {
    Permanent perm=it.next();
    if (perm.getOwnerId().equals(playerId)) {
      if (perm.getAttachedTo() != null) {
        Permanent attachedTo=getPermanent(perm.getAttachedTo());
        if (attachedTo != null) {
          attachedTo.removeAttachment(perm.getId(),this);
        }
      }
      it.remove();
    }
  }
  for (Iterator<StackObject> it=getStack().iterator(); it.hasNext(); ) {
    StackObject object=it.next();
    if (object.getControllerId().equals(playerId)) {
      it.remove();
    }
  }
  for (Iterator<Permanent> it=getBattlefield().getAllPermanents().iterator(); it.hasNext(); ) {
    Permanent perm=it.next();
    if (perm.getControllerId().equals(playerId)) {
      perm.moveToExile(null,"String_Node_Str",null,this);
    }
  }
}

Fixed version (ground truth):
/** 
 * 800.4a When a player leaves the game, all objects (see rule 109) owned by that player leave  the game and any effects which give that player control of any objects or players end. Then,  if that player controlled any objects on the stack not represented by cards, those objects  cease to exist. Then, if there are any objects still controlled by that player, those objects are exiled. This is not a state-based action. It happens as soon as the player leaves the game. If the player who left the game had priority at the time he or she left, priority passes to the next player in turn order who's still in the game. #
 * @param playerId 
 */
@Override public void leave(UUID playerId){
  Player player=getPlayer(playerId);
  player.leave();
  for (Iterator<Permanent> it=getBattlefield().getAllPermanents().iterator(); it.hasNext(); ) {
    Permanent perm=it.next();
    if (perm.getOwnerId().equals(playerId)) {
      if (perm.getAttachedTo() != null) {
        Permanent attachedTo=getPermanent(perm.getAttachedTo());
        if (attachedTo != null) {
          attachedTo.removeAttachment(perm.getId(),this);
        }
      }
      it.remove();
    }
  }
  this.getState().getContinuousEffects().removeInactiveEffects(this);
  for (Iterator<StackObject> it=getStack().iterator(); it.hasNext(); ) {
    StackObject object=it.next();
    if (object.getControllerId().equals(playerId)) {
      it.remove();
    }
  }
  for (Iterator<Permanent> it=getBattlefield().getAllPermanents().iterator(); it.hasNext(); ) {
    Permanent perm=it.next();
    if (perm.getControllerId().equals(playerId)) {
      perm.moveToExile(null,"String_Node_Str",null,this);
    }
  }
  Iterator it=gameCards.entrySet().iterator();
  while (it.hasNext()) {
    Entry<UUID,Card> entry=(Entry<UUID,Card>)it.next();
    Card card=entry.getValue();
    if (card.getOwnerId().equals(playerId)) {
      it.remove();
    }
  }
}