traverse_parents

# File lib/rubygems/util.rb, line 112
  def self.traverse_parents directory, &block
    return enum_for __method__, directory unless block_given?

    here = File.expand_path directory
    loop do
      Dir.chdir here, &block rescue Errno::EACCES

      new_here = File.expand_path('..', here)
      return if new_here == here # toplevel
      here = new_here
    end
  end