# File lib/rubygems/old_format.rb, line 36
  def self.from_file_by_path(file_path)
    unless File.exist?(file_path)
      raise Gem::Exception, "Cannot load gem file [#{file_path}]"
    end

    File.open(file_path, 'rb') do |file|
      from_io(file, file_path)
    end
  end