Is there a better way to pick up included files for 'rake package'?

gistfile1.rb

require 'rake/packagetask'
require 'bundler/gem_tasks'
require 'rubocop/rake_task'
require 'find'
require 'pathname'

ROOT_DIR = File.dirname(__FILE__)

spec = Gem::Specification::load("#{Dir.glob(ROOT_DIR + '/*.gemspec')[0]}")

task :rubocop do
  Rubocop::RakeTask.new
end

ignored = File.open("#{ROOT_DIR}/.gitignore").readlines.map { |f| f.chomp }
ignored += ['.git', '.gitignore' ]
Rake::PackageTask.new(spec.name, spec.version.to_s) do |p|
  p.need_tar_bz2 = p.need_zip = true
  included = []
  Find.find(ROOT_DIR) do |path|
    path = Pathname.new(path).relative_path_from(Pathname.new(ROOT_DIR)).to_s
    ok = true
    ignored.each do |ignore|
      if File.fnmatch(ignore, path)
        Find.prune if FileTest.directory?(path)
        ok = false
        break
      end
    end
    included << path if ok
  end
  p.package_files = included
end

task default: 'rubocop'

Yes, there is a much better way. Asked on IRC, and someone pointed to git ls-files used by bundler. Since I'm already loading my gemspec, and it uses the same method to fill in the files, I can just use this:

p.package_files = spec.files