Program: 134118
Project: 134118
Buggy source:
private boolean moveBlocks(){
  if (player.getWorld() != headblock.getWorld()) {
    cancel();
    return false;
  }
  Location headlocation=player.getEyeLocation();
  Location legslocation=player.getLocation();
  Vector headdirection=headlocation.toVector().subtract(headblocklocation.toVector()).normalize().multiply(.5);
  Vector legsdirection=legslocation.toVector().subtract(legsblocklocation.toVector()).normalize().multiply(.5);
  Block newheadblock=headblock;
  Block newlegsblock=legsblock;
  if (!headlocation.getBlock().equals(headblock)) {
    headblocklocation=headblocklocation.clone().add(headdirection);
    newheadblock=headblocklocation.getBlock();
  }
  if (!legslocation.getBlock().equals(legsblock)) {
    legsblocklocation=legsblocklocation.clone().add(legsdirection);
    newlegsblock=legsblocklocation.getBlock();
  }
  if (EarthMethods.isTransparentToEarthbending(player,newheadblock) && !newheadblock.isLiquid()) {
    GeneralMethods.breakBlock(newheadblock);
  }
 else   if (!EarthMethods.isEarthbendable(player,newheadblock) && !newheadblock.isLiquid() && newheadblock.getType() != Material.AIR) {
    cancel();
    return false;
  }
  if (EarthMethods.isTransparentToEarthbending(player,newlegsblock) && !newlegsblock.isLiquid()) {
    GeneralMethods.breakBlock(newlegsblock);
  }
 else   if (!EarthMethods.isEarthbendable(player,newlegsblock) && !newlegsblock.isLiquid() && newlegsblock.getType() != Material.AIR) {
    cancel();
    return false;
  }
  if (headblock.getLocation().distance(player.getEyeLocation()) > range || legsblock.getLocation().distance(player.getLocation()) > range) {
    cancel();
    return false;
  }
  if (!newheadblock.equals(headblock)) {
    new TempBlock(newheadblock,headtype,headdata);
    if (TempBlock.isTempBlock(headblock))     TempBlock.revertBlock(headblock,Material.AIR);
  }
  if (!newlegsblock.equals(legsblock)) {
    new TempBlock(newlegsblock,legstype,legsdata);
    if (TempBlock.isTempBlock(legsblock))     TempBlock.revertBlock(legsblock,Material.AIR);
  }
  headblock=newheadblock;
  legsblock=newlegsblock;
  return true;
}

Fixed version (ground truth):
private boolean moveBlocks(){
  if (!player.getWorld().equals(headblock.getWorld())) {
    cancel();
    return false;
  }
  Location headlocation=player.getEyeLocation();
  Location legslocation=player.getLocation();
  Vector headdirection=headlocation.toVector().subtract(headblocklocation.toVector()).normalize().multiply(.5);
  Vector legsdirection=legslocation.toVector().subtract(legsblocklocation.toVector()).normalize().multiply(.5);
  Block newheadblock=headblock;
  Block newlegsblock=legsblock;
  if (!headlocation.getBlock().equals(headblock)) {
    headblocklocation=headblocklocation.clone().add(headdirection);
    newheadblock=headblocklocation.getBlock();
  }
  if (!legslocation.getBlock().equals(legsblock)) {
    legsblocklocation=legsblocklocation.clone().add(legsdirection);
    newlegsblock=legsblocklocation.getBlock();
  }
  if (EarthMethods.isTransparentToEarthbending(player,newheadblock) && !newheadblock.isLiquid()) {
    GeneralMethods.breakBlock(newheadblock);
  }
 else   if (!EarthMethods.isEarthbendable(player,newheadblock) && !newheadblock.isLiquid() && newheadblock.getType() != Material.AIR) {
    cancel();
    return false;
  }
  if (EarthMethods.isTransparentToEarthbending(player,newlegsblock) && !newlegsblock.isLiquid()) {
    GeneralMethods.breakBlock(newlegsblock);
  }
 else   if (!EarthMethods.isEarthbendable(player,newlegsblock) && !newlegsblock.isLiquid() && newlegsblock.getType() != Material.AIR) {
    cancel();
    return false;
  }
  if (headblock.getLocation().distance(player.getEyeLocation()) > range || legsblock.getLocation().distance(player.getLocation()) > range) {
    cancel();
    return false;
  }
  if (!newheadblock.equals(headblock)) {
    new TempBlock(newheadblock,headtype,headdata);
    if (TempBlock.isTempBlock(headblock))     TempBlock.revertBlock(headblock,Material.AIR);
  }
  if (!newlegsblock.equals(legsblock)) {
    new TempBlock(newlegsblock,legstype,legsdata);
    if (TempBlock.isTempBlock(legsblock))     TempBlock.revertBlock(legsblock,Material.AIR);
  }
  headblock=newheadblock;
  legsblock=newlegsblock;
  return true;
}