jruby-akka exception after hot swapping actor

AkkaUntypedActor.scala

import akka.actor._

import org.jruby.Ruby
import org.jruby.RubyClass
import org.jruby.RubyModule
import org.jruby.RubyObject
import org.jruby.anno.JRubyMethod
import org.jruby.anno.JRubyClass
import org.jruby.runtime.ObjectAllocator
import org.jruby.runtime.ThreadContext
import org.jruby.runtime.builtin.IRubyObject
import org.jruby.javasupport.JavaUtil
import org.jruby.runtime.Block
import org.jruby.runtime.Visibility._

@JRubyClass(name=Array("Actor"))
class AkkaUntypedActor(val runtime: Ruby, val klass: RubyClass) extends RubyObject(runtime, klass) {
  var actor: ActorRef = null

  protected class InnerUntypedActor(runtime: Ruby, context: ThreadContext, parent: RubyObject, block: Block) extends UntypedActor {
    def onReceive(msg: Any) {
      val args = Array(JavaUtil.convertJavaToRuby(runtime,msg))
      parent.instance_exec(context, args, block)
    }
  }

  @JRubyMethod(visibility = PRIVATE)
  def initialize(context: ThreadContext, block: Block) = {
    val self = this
    actor = Actors.actorOf(new UntypedActorFactory() {
      def create() = {
        new InnerUntypedActor(context.getRuntime(), context, self, block)
      }
    })
    this
  }

  @JRubyMethod(name=Array("reply"))
  def replyUnsafe(context: ThreadContext, msg: IRubyObject) {
    actor.replyUnsafe(msg)
  }

  @JRubyMethod(name=Array("send_request_reply"))
  def sendRequestReply(context: ThreadContext, msg: IRubyObject) = {
    JavaUtil.convertJavaToRuby(context.getRuntime(), actor !! (msg))
  }

  @JRubyMethod(name=Array("send_request_reply_future"))
  def sendRequestReplyFuture(context: ThreadContext, msg: IRubyObject) = {
    JavaUtil.convertJavaToRuby(context.getRuntime(), actor !!! (msg))
  }

  @JRubyMethod(name=Array("<<"))
  def sendMesssage(context: ThreadContext, msg: IRubyObject) {
    actor ! (msg)
  }

  @JRubyMethod
  def stop(context: ThreadContext) {
    actor.stop()
  }

  @JRubyMethod
  def start(context: ThreadContext) {
    actor.start()
  }
  
  @JRubyMethod(name=Array("hot_swap"))
  def hotSwap(context: ThreadContext, block: Block) {
    val parent = this
    actor ! HotSwap( self => {
      case msg => {
        val args = Array(JavaUtil.convertJavaToRuby(runtime,msg))
        	parent.instance_exec(context, args, block)
      }
    })
  }
}

object AkkaUntypedActor {
  def createActorClass(runtime: Ruby, akkaModule: RubyModule) = {
    val actorc = runtime.defineClassUnder("Actor", runtime.getObject(), ActorAllocator, akkaModule)
    actorc.setReifiedClass(classOf[AkkaUntypedActor])
    actorc.kindOf = new RubyModule.KindOf() {
      override def isKindOf(obj: IRubyObject, aType: RubyModule) = {
        obj.isInstanceOf[AkkaUntypedActor]
      }
    }
    actorc.defineAnnotatedMethods(classOf[AkkaUntypedActor])
    actorc
  }

  object ActorAllocator extends ObjectAllocator() {
	def allocate(runtime: Ruby, klass: RubyClass) = {
      new AkkaUntypedActor(runtime, klass)
    }
  }
}

irb session

jruby-1.6.3 :001 > require 'lib/jruby-akka'
 => true 
jruby-1.6.3 :002 > a = Akka::Actor.new do |m|
jruby-1.6.3 :003 >     puts m
jruby-1.6.3 :004?>   end

Can't load 'akka.conf'.
One of the three ways of locating the 'akka.conf' file needs to be defined:
	1. Define the '-Dakka.config=...' system property option.
	2. Put the 'akka.conf' file on the classpath.
	3. Define 'AKKA_HOME' environment variable pointing to the root of the Akka distribution.
I have no way of finding the 'akka.conf' configuration file.
Using default values everywhere.
 => #<Akka::Actor:0x31455cf4> 
jruby-1.6.3 :005 > a.start
 => nil 
jruby-1.6.3 :006 > a << :foo
 => nil 
foo
jruby-1.6.3 :007 > a.hot_swap do |m|
jruby-1.6.3 :008 >     puts "swapped #{m}"
jruby-1.6.3 :009?>   end
 => nil 
jruby-1.6.3 :010 > a << :foo
 => nil 
swapped foo
Java::JavaLang::NullPointerException: 
	from org.jruby.runtime.scope.NoVarsDynamicScope.setValue(NoVarsDynamicScope.java:87)
	from org.jruby.runtime.scope.NoVarsDynamicScope.setValue(NoVarsDynamicScope.java:87)
	from org.jruby.ast.DAsgnNode.interpret(DAsgnNode.java:110)
	from org.jruby.ast.NewlineNode.interpret(NewlineNode.java:104)
	from org.jruby.ast.BlockNode.interpret(BlockNode.java:71)
	from org.jruby.ast.RescueNode.executeBody(RescueNode.java:216)
	from org.jruby.ast.RescueNode.interpretWithJavaExceptions(RescueNode.java:120)
	from org.jruby.ast.RescueNode.interpret(RescueNode.java:110)
	from org.jruby.ast.BeginNode.interpret(BeginNode.java:83)
	from org.jruby.ast.NewlineNode.interpret(NewlineNode.java:104)
	from org.jruby.ast.BlockNode.interpret(BlockNode.java:71)
	from org.jruby.evaluator.ASTInterpreter.INTERPRET_BLOCK(ASTInterpreter.java:112)
	from org.jruby.runtime.InterpretedBlock.evalBlockBody(InterpretedBlock.java:374)
	from org.jruby.runtime.InterpretedBlock.yield(InterpretedBlock.java:295)
	from org.jruby.runtime.InterpretedBlock.yieldSpecific(InterpretedBlock.java:229)
	from org.jruby.runtime.Block.yieldSpecific(Block.java:99)
... 85 levels...
	from org.jruby.ast.BlockNode.interpret(BlockNode.java:71)
	from org.jruby.evaluator.ASTInterpreter.INTERPRET_METHOD(ASTInterpreter.java:75)
	from org.jruby.internal.runtime.methods.InterpretedMethod.call(InterpretedMethod.java:190)
	from org.jruby.internal.runtime.methods.DefaultMethod.call(DefaultMethod.java:179)
	from org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:312)
	from org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:169)
	from Users.corpsi.$_dot_rvm.rubies.jruby_minus_1_dot_6_dot_3.bin.jirb.__file__(/Users/corpsi/.rvm/rubies/jruby-1.6.3/bin/jirb:17)
	from Users.corpsi.$_dot_rvm.rubies.jruby_minus_1_dot_6_dot_3.bin.jirb.load(/Users/corpsi/.rvm/rubies/jruby-1.6.3/bin/jirb)
	from org.jruby.Ruby.runScript(Ruby.java:671)
	from org.jruby.Ruby.runNormally(Ruby.java:575)
	from org.jruby.Ruby.runFromMain(Ruby.java:424)
	from org.jruby.Main.doRunFromMain(Main.java:278)
	from org.jruby.Main.internalRun(Main.java:198)
	from org.jruby.Main.run(Main.java:164)
	from org.jruby.Main.run(Main.java:148)
	from org.jruby.Main.main(Main.java:128)jruby-1.6.3 :011 > 

I got the same error, namely:

   NoVarsDynamicScope.java:87:in `setValue': java.lang.NullPointerException

simply by typing:

   jruby -S warble -T

after porting my JRuby servlet development environment from Ubuntu 12.04 to Fedora 14 using all of the same revisions of all of the same gems.