症状 rubygems を 3.1.4 に更新する際に以下のエラーが出る。 $ sudo gem update --system 3.1.4 (中略) Loading the rubygems/defaults/operating_system.rb file caused an error. This file is owned by your OS, not by rubygems upstream. Please find out which OS package this file belongs to and follow the guidelines from your OS to…