Gem::Commands::UnpackCommand#find_in_cache

# File tmp/rubies/ruby-3.0.5/lib/rubygems/commands/unpack_command.rb, line 128
def find_in_cache(filename)
  Gem.path.each do |path|
    this_path = File.join(path, "cache", filename)
    return this_path if File.exist? this_path
  end

  return nil
end