Program: 27658
Project: 27658
Buggy source:
@Override public boolean setLocation(Location location){
  if (isRemoved()) {
    return false;
  }
  Entity spongeEntity=(Entity)this;
  net.minecraft.entity.Entity thisEntity=(net.minecraft.entity.Entity)spongeEntity;
  net.minecraft.entity.Entity passenger=thisEntity.riddenByEntity;
  ArrayDeque<net.minecraft.entity.Entity> passengers=new ArrayDeque<net.minecraft.entity.Entity>();
  while (passenger != null) {
    if (passenger instanceof EntityPlayerMP && !this.worldObj.isRemote) {
      ((EntityPlayerMP)passenger).mountEntity(null);
    }
    net.minecraft.entity.Entity nextPassenger=null;
    if (passenger.riddenByEntity != null) {
      nextPassenger=passenger.riddenByEntity;
      this.riddenByEntity.mountEntity(null);
    }
    passengers.add(passenger);
    passenger=nextPassenger;
  }
  net.minecraft.world.World nmsWorld=null;
  if (location.getExtent() instanceof World && ((net.minecraft.world.World)location.getExtent() != this.worldObj)) {
    if (!(thisEntity instanceof EntityPlayer)) {
      nmsWorld=(net.minecraft.world.World)location.getExtent();
      teleportEntity(thisEntity,location,thisEntity.dimension,nmsWorld.provider.getDimensionId());
    }
  }
 else {
    setPosition(location.getPosition().getX(),location.getPosition().getY(),location.getPosition().getZ());
  }
  net.minecraft.entity.Entity lastPassenger=thisEntity;
  while (!passengers.isEmpty()) {
    net.minecraft.entity.Entity passengerEntity=passengers.remove();
    if (nmsWorld != null) {
      teleportEntity(passengerEntity,location,passengerEntity.dimension,nmsWorld.provider.getDimensionId());
    }
    if (passengerEntity instanceof EntityPlayerMP && !this.worldObj.isRemote) {
      ((ISpongeEntity)passengerEntity).setIsTeleporting(true);
      ((ISpongeEntity)passengerEntity).setTeleportVehicle(lastPassenger);
    }
 else {
      passengerEntity.mountEntity(lastPassenger);
    }
    lastPassenger=passengerEntity;
  }
  return true;
}

Fixed version (ground truth):
@Override public boolean setLocation(Location location){
  if (isRemoved()) {
    return false;
  }
  Entity spongeEntity=(Entity)this;
  net.minecraft.entity.Entity thisEntity=(net.minecraft.entity.Entity)spongeEntity;
  net.minecraft.entity.Entity passenger=thisEntity.riddenByEntity;
  ArrayDeque<net.minecraft.entity.Entity> passengers=new ArrayDeque<net.minecraft.entity.Entity>();
  while (passenger != null) {
    if (passenger instanceof EntityPlayerMP && !this.worldObj.isRemote) {
      ((EntityPlayerMP)passenger).mountEntity(null);
    }
    net.minecraft.entity.Entity nextPassenger=null;
    if (passenger.riddenByEntity != null) {
      nextPassenger=passenger.riddenByEntity;
      this.riddenByEntity.mountEntity(null);
    }
    passengers.add(passenger);
    passenger=nextPassenger;
  }
  net.minecraft.world.World nmsWorld=null;
  if (location.getExtent() instanceof World && ((net.minecraft.world.World)location.getExtent() != this.worldObj)) {
    if (!(thisEntity instanceof EntityPlayer)) {
      nmsWorld=(net.minecraft.world.World)location.getExtent();
      teleportEntity(thisEntity,location,thisEntity.dimension,nmsWorld.provider.getDimensionId());
    }
  }
 else {
    setPosition(location.getPosition().getX(),location.getPosition().getY(),location.getPosition().getZ());
    if (thisEntity instanceof EntityPlayerMP) {
      ((EntityPlayerMP)thisEntity).playerNetServerHandler.setPlayerLocation(location.getPosition().getX(),location.getPosition().getY(),location.getPosition().getZ(),thisEntity.rotationYaw,thisEntity.rotationPitch);
    }
  }
  net.minecraft.entity.Entity lastPassenger=thisEntity;
  while (!passengers.isEmpty()) {
    net.minecraft.entity.Entity passengerEntity=passengers.remove();
    if (nmsWorld != null) {
      teleportEntity(passengerEntity,location,passengerEntity.dimension,nmsWorld.provider.getDimensionId());
    }
    if (passengerEntity instanceof EntityPlayerMP && !this.worldObj.isRemote) {
      ((ISpongeEntity)passengerEntity).setIsTeleporting(true);
      ((ISpongeEntity)passengerEntity).setTeleportVehicle(lastPassenger);
    }
 else {
      passengerEntity.mountEntity(lastPassenger);
    }
    lastPassenger=passengerEntity;
  }
  return true;
}