A very hacky way to require gems from outside a bundler environment

require_external_gem.rb

require 'shellwords'

def require_external_gem(name)
  return require name unless defined? Bundler

  dir = Bundler.with_clean_env do
    `echo #{name.shellescape} | ruby -e \
      'puts Gem::Specification.find_by_name(STDIN.read.chomp).gem_dir'`.chomp
  end

  $: << File.join(dir, "lib")
  require name
end