/usr/lib/ruby/ is in ruby-mousetrap-rails 1.4.6-5.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/mousetrap-rails.rb
/usr/lib/ruby/vendor_ruby/generators/
/usr/lib/ruby/vendor_ruby/generators/mousetrap/
/usr/lib/ruby/vendor_ruby/generators/mousetrap/install/
/usr/lib/ruby/vendor_ruby/generators/mousetrap/install/install_generator.rb
/usr/lib/ruby/vendor_ruby/generators/mousetrap/install/USAGE
/usr/lib/ruby/vendor_ruby/generators/mousetrap/install/templates/
/usr/lib/ruby/vendor_ruby/generators/mousetrap/install/templates/keybindings.js.coffee
/usr/lib/ruby/vendor_ruby/generators/mousetrap/install/templates/application.js
/usr/lib/ruby/vendor_ruby/generators/mousetrap/install/templates/application.css
/usr/lib/ruby/vendor_ruby/mousetrap-rails/
/usr/lib/ruby/vendor_ruby/mousetrap-rails/railtie.rb
/usr/lib/ruby/vendor_ruby/mousetrap-rails/version.rb
/usr/lib/ruby/vendor_ruby/mousetrap-rails/engine.rb