Why do I get a NoSuchMethod error running Warbler?

I'm getting the following error when running warble under both jRuby 1.3 and 1.4. I'm new to warbler, any suggestions what to try next?

$ warble war 
WarblerWar.java:70:in `addEntry': java.lang.NoSuchMethodError:
    org.jruby.util.ByteList.getUnsafeBytes()[B
    from WarblerWar.java:63:in `addEntries'

Other info that might help: It's a tiny sinatra app, my config/warble.rb file looks like http://gist.github.com/91801#file_warble.rb

I also tried switching the version of jruby-jars from 1.4 to 1.开发者_开发问答3

$ jruby -S gem list --local

*** LOCAL GEMS ***

jruby-jars (1.3.1)
jruby-rack (0.9.7)
rack (1.1.0)
rake (0.8.7)
rspec (1.2.6)
rubyzip (0.9.4)
sinatra (1.0)
sources (0.0.1)
warbler (1.0)

Sorry Ben, this is my fault. The new release is apparently not working with JRuby prior to the unreleased version 1.5. To fix this, you can comment out the "require 'warbler_war'" line near the bottom of lib/warbler/war.rb. I'll release a fix for this shortly.