Program: 25243
Project: 25243
Buggy source:
public static int promote(Player player,String[] args){
  if (!player.canUseCommand("String_Node_Str"))   return EXIT_FAIL;
  if (args.length < 1) {
    vMinecraftChat.sendMessage(player,Colors.Rose + "String_Node_Str");
    return EXIT_SUCCESS;
  }
  Player target=etc.getServer().matchPlayer(args[0]);
  if (target == null) {
    vMinecraftChat.sendMessage(player,Colors.Rose + "String_Node_Str");
    return EXIT_SUCCESS;
  }
  String[] ranks=vMinecraftSettings.getInstance().getRanks();
  String[] tarGroups=target.getGroups();
  int tarRank=0, tarPos=0;
  boolean leave=false;
  for (  String rank : ranks) {
    for (    String group : tarGroups) {
      if (rank.equalsIgnoreCase(group)) {
        leave=true;
        break;
      }
 else       tarPos++;
    }
    if (leave)     break;
    tarRank++;
    tarPos=0;
  }
  if (!leave) {
    tarRank=0;
    tarPos=0;
    if (tarGroups != null) {
      String[] tempGroups=new String[tarGroups.length + 1];
      System.arraycopy(tarGroups,0,tempGroups,1,tarGroups.length);
      tarGroups=tempGroups;
    }
 else     tarGroups=new String[1];
  }
  leave=false;
  String[] myGroups=player.getGroups();
  int myRank=0;
  for (  String rank : ranks) {
    for (    String group : myGroups)     if (rank.equalsIgnoreCase(group)) {
      log.log(Level.INFO,myRank + "String_Node_Str");
      leave=true;
      break;
    }
    if (leave)     break;
    myRank++;
  }
  if (!leave)   myRank=0;
  log.log(Level.INFO,myRank + "String_Node_Str" + tarRank);
  if (myRank <= tarRank + 1) {
    vMinecraftChat.sendMessage(player,Colors.Rose + "String_Node_Str" + "String_Node_Str");
    return EXIT_SUCCESS;
  }
  tarGroups[tarPos]=ranks[tarRank + 1];
  target.setGroups(tarGroups);
  FlatFileSource ffs=new FlatFileSource();
  if (!ffs.doesPlayerExist(target.getName())) {
    vMinecraftChat.sendMessage(player,Colors.Rose + "String_Node_Str");
    ffs.addPlayer(target);
  }
 else {
    ffs.modifyPlayer(target);
  }
  vMinecraftChat.sendMessage(player,Colors.Rose + target.getName() + "String_Node_Str"+ ranks[tarRank + 1]+ "String_Node_Str");
  vMinecraftChat.sendMessage(target,Colors.Rose + "String_Node_Str" + ranks[tarRank + 1]+ "String_Node_Str");
  return EXIT_SUCCESS;
}

Fixed version (ground truth):
public static int promote(Player player,String[] args){
  if (!player.canUseCommand("String_Node_Str"))   return EXIT_FAIL;
  if (args.length < 1) {
    vMinecraftChat.sendMessage(player,Colors.Rose + "String_Node_Str");
    return EXIT_SUCCESS;
  }
  Player target=etc.getServer().matchPlayer(args[0]);
  if (target == null) {
    vMinecraftChat.sendMessage(player,Colors.Rose + "String_Node_Str");
    return EXIT_SUCCESS;
  }
  String[] ranks=vMinecraftSettings.getInstance().getRanks();
  String[] tarGroups=target.getGroups();
  int tarRank=0, tarPos=0;
  boolean leave=false;
  for (  String rank : ranks) {
    for (    String group : tarGroups) {
      if (rank.equalsIgnoreCase(group)) {
        leave=true;
        break;
      }
 else       tarPos++;
    }
    if (leave)     break;
    tarRank++;
    tarPos=0;
  }
  if (!leave) {
    tarRank=0;
    tarPos=0;
    if (tarGroups != null) {
      String[] tempGroups=new String[tarGroups.length + 1];
      System.arraycopy(tarGroups,0,tempGroups,1,tarGroups.length);
      tarGroups=tempGroups;
    }
 else     tarGroups=new String[1];
  }
  leave=false;
  String[] myGroups=player.getGroups();
  int myRank=0;
  for (  String rank : ranks) {
    for (    String group : myGroups)     if (rank.equalsIgnoreCase(group)) {
      leave=true;
      break;
    }
    if (leave)     break;
    myRank++;
  }
  if (!leave)   myRank=0;
  if (myRank <= tarRank + 1) {
    vMinecraftChat.sendMessage(player,Colors.Rose + "String_Node_Str" + "String_Node_Str");
    return EXIT_SUCCESS;
  }
  tarGroups[tarPos]=ranks[tarRank + 1];
  target.setGroups(tarGroups);
  FlatFileSource ffs=new FlatFileSource();
  if (!ffs.doesPlayerExist(target.getName())) {
    vMinecraftChat.sendMessage(player,Colors.Rose + "String_Node_Str");
    ffs.addPlayer(target);
  }
 else {
    ffs.modifyPlayer(target);
  }
  vMinecraftChat.sendMessage(player,Colors.Rose + target.getName() + "String_Node_Str"+ ranks[tarRank + 1]+ "String_Node_Str");
  vMinecraftChat.sendMessage(target,Colors.Rose + "String_Node_Str" + ranks[tarRank + 1]+ "String_Node_Str");
  return EXIT_SUCCESS;
}