Running commands in a Bundler-enabled app that has a Git repo attached to it makes running Bundler in subshells a pain. Bundler.with_clean_env gets close, but still leaves enough of Bundler around to be unpleasant. This kills it dead in subshells:

module Bundler
  class << self
    def with_sparkling_clean_env
      oenv = ENV.to_hash

      %w{BUNDLE_GEMFILE RUBYOPT GEM_HOME GIT_DIR GIT_WORK_TREE}.each { |key| ENV.delete(key) }

      yield

      ENV.replace(oenv)
    end
  end
end