Program: 81427
Project: 81427
Buggy source:
/** 
 * Parse jail command and prepare user for jailing (if he is online, he will be instantly jailed. Otherwise, he will be jailed first time when he comes online)
 * @param sender CommandSender that send this command
 * @param args Arguments for the command. 0 = name, 1 = time, 2 = jailname:cellname, 3 = reason
 */
public static void PrepareJail(CommandSender sender,String args[]){
  String playername;
  int time=-1;
  String jailname="String_Node_Str";
  if (args.length < 1) {
    if (sender != null)     Util.Message("String_Node_Str",sender);
    return;
  }
  if (Jail.zones.size() < 1) {
    if (sender != null)     Util.Message("String_Node_Str",sender);
    return;
  }
  if (Jail.prisoners.containsKey(args[0].toLowerCase())) {
    JailPrisoner prisoner=Jail.prisoners.get(args[0].toLowerCase());
    Player player=Jail.instance.getServer().getPlayer(prisoner.getName());
    if (player != null) {
      player.teleport(prisoner.getTeleportLocation());
      if (sender != null)       Util.Message("String_Node_Str",sender);
    }
 else {
      if (sender != null)       Util.Message("String_Node_Str",sender);
    }
    return;
  }
  playername=args[0].toLowerCase();
  if (args.length > 1)   time=Integer.valueOf(args[1]);
  if (args.length > 2)   jailname=args[2].toLowerCase();
  String reason="String_Node_Str";
  if (args.length > 3) {
    for (int i=3; i < args.length; i++) {
      reason+="String_Node_Str" + args[i];
    }
    if (reason.length() > 250) {
      if (sender != null)       Util.Message("String_Node_Str",sender);
      return;
    }
  }
  if (jailname.equals(Settings.NearestJailCode))   jailname="String_Node_Str";
  String cellname=null;
  if (jailname.contains("String_Node_Str")) {
    cellname=jailname.split("String_Node_Str")[1];
    jailname=jailname.split("String_Node_Str")[0];
  }
  String jailer;
  if (sender instanceof Player)   jailer=((Player)sender).getName();
 else   jailer="String_Node_Str";
  Player player=Jail.instance.getServer().getPlayer(playername);
  if (player == null) {
    JailPrisoner prisoner=new JailPrisoner(playername,time * 6,jailname,null,true,"String_Node_Str",reason,Settings.AutomaticMute,"String_Node_Str",jailer);
    JailCell cell=prisoner.getJail().getRequestedCell(prisoner);
    if (cell != null && (cell.getPlayerName() == null || !cell.getPlayerName().trim().equals("String_Node_Str"))) {
      cell.setPlayerName(prisoner.getName());
      cell.update();
    }
    InputOutput.InsertPrisoner(prisoner);
    Jail.prisoners.put(prisoner.getName(),prisoner);
    Util.Message("String_Node_Str",sender);
  }
 else {
    JailPrisoner prisoner=new JailPrisoner(playername,time * 6,jailname,cellname,false,"String_Node_Str",reason,Settings.AutomaticMute,"String_Node_Str",jailer);
    Jail(prisoner,player);
    Util.Message("String_Node_Str",sender);
  }
}

Fixed version (ground truth):
/** 
 * Parse jail command and prepare user for jailing (if he is online, he will be instantly jailed. Otherwise, he will be jailed first time when he comes online)
 * @param sender CommandSender that send this command
 * @param args Arguments for the command. 0 = name, 1 = time, 2 = jailname:cellname, 3 = reason
 */
public static void PrepareJail(CommandSender sender,String args[]){
  String playername;
  int time=-1;
  String jailname="String_Node_Str";
  if (args.length < 1) {
    if (sender != null)     Util.Message("String_Node_Str",sender);
    return;
  }
  if (Jail.zones.size() < 1) {
    if (sender != null)     Util.Message("String_Node_Str",sender);
    return;
  }
  if (Jail.prisoners.containsKey(args[0].toLowerCase())) {
    JailPrisoner prisoner=Jail.prisoners.get(args[0].toLowerCase());
    Player player=Jail.instance.getServer().getPlayer(prisoner.getName());
    if (player != null) {
      player.teleport(prisoner.getTeleportLocation());
      if (sender != null)       Util.Message("String_Node_Str",sender);
    }
 else {
      if (sender != null)       Util.Message("String_Node_Str",sender);
    }
    return;
  }
  playername=args[0].toLowerCase();
  if (args.length > 1)   time=Integer.valueOf(args[1]);
  if (args.length > 2)   jailname=args[2].toLowerCase();
  String reason="String_Node_Str";
  if (args.length > 3) {
    for (int i=3; i < args.length; i++) {
      reason+="String_Node_Str" + args[i];
    }
    if (reason.length() > 250) {
      if (sender != null)       Util.Message("String_Node_Str",sender);
      return;
    }
  }
  if (jailname.equals(Settings.NearestJailCode))   jailname="String_Node_Str";
  String cellname=null;
  if (jailname.contains("String_Node_Str")) {
    cellname=jailname.split("String_Node_Str")[1];
    jailname=jailname.split("String_Node_Str")[0];
  }
  String jailer;
  if (sender instanceof Player)   jailer=((Player)sender).getName();
 else   jailer="String_Node_Str";
  Player player=Jail.instance.getServer().getPlayer(playername);
  if (player == null) {
    JailPrisoner prisoner=new JailPrisoner(playername,time * 6,jailname,cellname,true,"String_Node_Str",reason,Settings.AutomaticMute,"String_Node_Str",jailer);
    if (prisoner.getJail() != null) {
      JailCell cell=prisoner.getJail().getRequestedCell(prisoner);
      if (cell != null && (cell.getPlayerName() == null || !cell.getPlayerName().trim().equals("String_Node_Str"))) {
        cell.setPlayerName(prisoner.getName());
        cell.update();
      }
    }
    InputOutput.InsertPrisoner(prisoner);
    Jail.prisoners.put(prisoner.getName(),prisoner);
    Util.Message("String_Node_Str",sender);
  }
 else {
    playername=player.getName().toLowerCase();
    JailPrisoner prisoner=new JailPrisoner(playername,time * 6,jailname,cellname,false,"String_Node_Str",reason,Settings.AutomaticMute,"String_Node_Str",jailer);
    Jail(prisoner,player);
    Util.Message("String_Node_Str",sender);
  }
}