Program: 81428
Project: 81428
Buggy source:
/** 
 * Performs jailing of specified JailPrisoner.  If you just want to jail someone, I recommend using JailAPI.jailPlayer,  because it supports offline jail and it's easier to do.
 * @param prisoner JailPrisoner class of the new prisoner. Must be already inserted into database
 * @param player Player that will be teleported
 */
public static void Jail(JailPrisoner prisoner,Player player){
  prisoner.SetBeingReleased(true);
  JailZone jail=prisoner.getJail();
  if (jail == null) {
    jail=JailZoneManager.findNearestJail(player.getLocation());
    prisoner.setJail(jail);
  }
  prisoner.setOfflinePending(false);
  if (prisoner.getReason().isEmpty())   Util.Message(Settings.MessageJail,player);
 else   Util.Message(Settings.MessageJailReason.replace("String_Node_Str",prisoner.getReason()),player);
  if (Settings.DeleteInventoryOnJail)   player.getInventory().clear();
  JailCell cell=jail.getRequestedCell(prisoner);
  if (cell == null || (cell.getPlayerName() != null && !cell.getPlayerName().equals("String_Node_Str") && !cell.getPlayerName().equals(prisoner.getName()))) {
    cell=null;
    cell=jail.getEmptyCell();
  }
  if (cell != null) {
    cell.setPlayerName(player.getName());
    prisoner.setCell(cell);
    prisoner.updateSign();
    if (Settings.StoreInventory && cell.getChest() != null) {
      Chest chest=cell.getChest();
      chest.getInventory().clear();
      for (int i=0; i < player.getInventory().getSize(); i++) {
        if (chest.getInventory().getSize() <= Util.getNumberOfOccupiedItemSlots(chest.getInventory().getContents()))         break;
        if (player.getInventory().getItem(i) == null || player.getInventory().getItem(i).getType() == Material.AIR)         continue;
        chest.getInventory().addItem(player.getInventory().getItem(i));
        player.getInventory().clear(i);
      }
      if (cell.getSecondChest() != null) {
        chest=cell.getSecondChest();
        chest.getInventory().clear();
        for (int i=0; i < player.getInventory().getSize(); i++) {
          if (chest.getInventory().getSize() <= Util.getNumberOfOccupiedItemSlots(chest.getInventory().getContents()))           break;
          if (player.getInventory().getItem(i) == null || player.getInventory().getItem(i).getType() == Material.AIR)           continue;
          chest.getInventory().addItem(player.getInventory().getItem(i));
          player.getInventory().clear(i);
        }
      }
    }
    cell.update();
  }
  player.teleport(prisoner.getTeleportLocation());
  if (Settings.StoreInventory) {
    prisoner.storeInventory(player.getInventory());
    player.getInventory().clear();
  }
  if (Jail.prisoners.containsKey(prisoner.getName()))   InputOutput.UpdatePrisoner(prisoner);
 else   InputOutput.InsertPrisoner(prisoner);
  Jail.prisoners.put(prisoner.getName(),prisoner);
  prisoner.SetBeingReleased(false);
  for (  String s : Settings.ExecutedCommandsOnJail) {
    CraftServer cs=(CraftServer)Jail.instance.getServer();
    CommandSender coms=new ConsoleCommandSender(Jail.instance.getServer());
    cs.dispatchCommand(coms,s.replace("String_Node_Str",player.getName()));
  }
}

Fixed version (ground truth):
/** 
 * Performs jailing of specified JailPrisoner.  If you just want to jail someone, I recommend using JailAPI.jailPlayer,  because it supports offline jail and it's easier to do.
 * @param prisoner JailPrisoner class of the new prisoner. Must be already inserted into database
 * @param player Player that will be teleported
 */
public static void Jail(JailPrisoner prisoner,Player player){
  if (!prisoner.getName().equals(player.getName().toLowerCase()))   return;
  prisoner.SetBeingReleased(true);
  JailZone jail=prisoner.getJail();
  if (jail == null) {
    jail=JailZoneManager.findNearestJail(player.getLocation());
    prisoner.setJail(jail);
  }
  prisoner.setOfflinePending(false);
  if (prisoner.getReason().isEmpty())   Util.Message(Settings.MessageJail,player);
 else   Util.Message(Settings.MessageJailReason.replace("String_Node_Str",prisoner.getReason()),player);
  if (Settings.DeleteInventoryOnJail)   player.getInventory().clear();
  JailCell cell=jail.getRequestedCell(prisoner);
  if (cell == null || (cell.getPlayerName() != null && !cell.getPlayerName().equals("String_Node_Str") && !cell.getPlayerName().equals(prisoner.getName()))) {
    cell=null;
    cell=jail.getEmptyCell();
  }
  if (cell != null) {
    cell.setPlayerName(player.getName());
    prisoner.setCell(cell);
    prisoner.updateSign();
    if (Settings.StoreInventory && cell.getChest() != null) {
      Chest chest=cell.getChest();
      chest.getInventory().clear();
      for (int i=0; i < player.getInventory().getSize(); i++) {
        if (chest.getInventory().getSize() <= Util.getNumberOfOccupiedItemSlots(chest.getInventory().getContents()))         break;
        if (player.getInventory().getItem(i) == null || player.getInventory().getItem(i).getType() == Material.AIR)         continue;
        chest.getInventory().addItem(player.getInventory().getItem(i));
        player.getInventory().clear(i);
      }
      if (cell.getSecondChest() != null) {
        chest=cell.getSecondChest();
        chest.getInventory().clear();
        for (int i=0; i < player.getInventory().getSize(); i++) {
          if (chest.getInventory().getSize() <= Util.getNumberOfOccupiedItemSlots(chest.getInventory().getContents()))           break;
          if (player.getInventory().getItem(i) == null || player.getInventory().getItem(i).getType() == Material.AIR)           continue;
          chest.getInventory().addItem(player.getInventory().getItem(i));
          player.getInventory().clear(i);
        }
      }
    }
    cell.update();
  }
  player.teleport(prisoner.getTeleportLocation());
  if (Settings.StoreInventory) {
    prisoner.storeInventory(player.getInventory());
    player.getInventory().clear();
  }
  if (Jail.prisoners.containsKey(prisoner.getName()))   InputOutput.UpdatePrisoner(prisoner);
 else   InputOutput.InsertPrisoner(prisoner);
  Jail.prisoners.put(prisoner.getName(),prisoner);
  prisoner.SetBeingReleased(false);
  for (  String s : Settings.ExecutedCommandsOnJail) {
    CraftServer cs=(CraftServer)Jail.instance.getServer();
    CommandSender coms=new ConsoleCommandSender(Jail.instance.getServer());
    cs.dispatchCommand(coms,s.replace("String_Node_Str",player.getName()));
  }
}