Program: 44731
Project: 44731
Buggy source:
public void jailPlayer(CommandSender sender,String[] args){
  Player player=this.getServer().getPlayer(args[0]);
  if (player == null) {
    sender.sendMessage(ChatColor.RED + "String_Node_Str" + args[0]+ "String_Node_Str");
    return;
  }
  args[0]=player.getName();
  if (!(args[0].equals(args[0].toLowerCase())) && jailed.getProperty(args[0].toLowerCase()) != null) {
    jailed.setProperty(args[0],args[0].toLowerCase());
    jailed.removeProperty(args[0].toLowerCase());
  }
  if (jailed.getProperty(args[0]) != null) {
    sender.sendMessage(ChatColor.RED + "String_Node_Str");
    return;
  }
  player.teleport(new Location(player.getWorld(),jailCoords[0],jailCoords[1],jailCoords[2]));
  if (useBukkitPermissions || !newPerms) {
    Object groupName;
    if (useBukkitPermissions) {
      List groups=bukkitPermissions.getGroups(player.getName());
      groupName=new ArrayList();
      for (      Object g : groups) {
        String gName=((Group)g).getName();
        gName=gName.replaceAll(Matcher.quoteReplacement("String_Node_Str"),"String_Node_Str");
        gName=gName.replaceAll(Matcher.quoteReplacement("String_Node_Str"),"String_Node_Str");
        gName=gName.replaceAll(Matcher.quoteReplacement("String_Node_Str"),"String_Node_Str");
        ((ArrayList)groupName).add(((Group)g).getName());
      }
    }
 else {
      groupName=permissions.getGroup(this.getServer().getWorlds().get(0).getName(),args[0]);
    }
    jailed.setProperty(args[0],groupName);
    this.setGroup(player,jailGroup);
  }
 else {
    String[] groupName=permissions.getGroups(this.getServer().getWorlds().get(0).getName(),args[0]);
    List groupList=Arrays.asList(groupName);
    if (groupList == null) {
      groupList=new ArrayList();
    }
    jailed.setProperty(args[0],groupList);
    List jailList=new ArrayList();
    jailList.add(jailGroup);
    this.setGroup(player,jailList);
  }
  jailed.save();
  if (!useBukkitPermissions)   perms.save();
  if (!useBukkitPermissions)   this.getServer().dispatchCommand(console,"String_Node_Str");
  sender.sendMessage(ChatColor.AQUA + "String_Node_Str");
}

Fixed version (ground truth):
public void jailPlayer(CommandSender sender,String[] args){
  Player player=this.getServer().getPlayer(args[0]);
  if (player == null) {
    sender.sendMessage(ChatColor.RED + "String_Node_Str" + args[0]+ "String_Node_Str");
    return;
  }
  args[0]=player.getName();
  if (!(args[0].equals(args[0].toLowerCase())) && jailed.getProperty(args[0].toLowerCase()) != null) {
    jailed.setProperty(args[0],args[0].toLowerCase());
    jailed.removeProperty(args[0].toLowerCase());
  }
  if (jailed.getProperty(args[0]) != null) {
    sender.sendMessage(ChatColor.RED + "String_Node_Str");
    return;
  }
  player.teleport(new Location(player.getWorld(),jailCoords[0],jailCoords[1],jailCoords[2]));
  if (useBukkitPermissions || !newPerms) {
    List<String> groupName;
    List groups=bukkitPermissions.getGroups(player.getName());
    groupName=new ArrayList();
    for (    Object g : groups) {
      String gName=((Group)g).getName();
      groupName.add(gName);
    }
    jailed.setProperty(args[0],groupName);
    this.setGroup(player,jailGroup);
  }
 else   if (!newPerms) {
    String groupName=permissions.getGroup(this.getServer().getWorlds().get(0).getName(),args[0]);
    jailed.setProperty(args[0],groupName);
    this.setGroup(player,jailGroup);
  }
 else {
    String[] groupName=permissions.getGroups(this.getServer().getWorlds().get(0).getName(),args[0]);
    List groupList=Arrays.asList(groupName);
    if (groupList == null) {
      groupList=new ArrayList();
    }
    jailed.setProperty(args[0],groupList);
    List jailList=new ArrayList();
    jailList.add(jailGroup);
    this.setGroup(player,jailList);
  }
  jailed.save();
  if (!useBukkitPermissions)   perms.save();
  if (!useBukkitPermissions)   this.getServer().dispatchCommand(console,"String_Node_Str");
  sender.sendMessage(ChatColor.AQUA + "String_Node_Str");
}