gemflat.rb

require "rubygems"
require "pry"
require "find"

cache = {}

Gem::Specification.find_all do |gemspec|
  gemspec.require_paths.each do |lib|
    prefix = File.join(gemspec.full_gem_path, lib)
    puts prefix + "/"
  end
end

gistfile1.txt

 % GEM_HOME=$PWD/vendor/bundle/jruby/1.9 GEM_PATH= RUBYLIB=$PWD/lib ruby gemflat.rb | xargs sh -c 'rsync -av "$@" build/flatgems2/' -