/usr/lib/ruby/vendor_ruby/ is in ruby-spring 1.3.6-2ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/spring/
/usr/lib/ruby/vendor_ruby/spring/application/
/usr/lib/ruby/vendor_ruby/spring/application/boot.rb
/usr/lib/ruby/vendor_ruby/spring/application.rb
/usr/lib/ruby/vendor_ruby/spring/application_manager.rb
/usr/lib/ruby/vendor_ruby/spring/binstub.rb
/usr/lib/ruby/vendor_ruby/spring/boot.rb
/usr/lib/ruby/vendor_ruby/spring/client/
/usr/lib/ruby/vendor_ruby/spring/client/binstub.rb
/usr/lib/ruby/vendor_ruby/spring/client/command.rb
/usr/lib/ruby/vendor_ruby/spring/client/help.rb
/usr/lib/ruby/vendor_ruby/spring/client/rails.rb
/usr/lib/ruby/vendor_ruby/spring/client/run.rb
/usr/lib/ruby/vendor_ruby/spring/client/status.rb
/usr/lib/ruby/vendor_ruby/spring/client/stop.rb
/usr/lib/ruby/vendor_ruby/spring/client/version.rb
/usr/lib/ruby/vendor_ruby/spring/client.rb
/usr/lib/ruby/vendor_ruby/spring/command_wrapper.rb
/usr/lib/ruby/vendor_ruby/spring/commands/
/usr/lib/ruby/vendor_ruby/spring/commands/rails.rb
/usr/lib/ruby/vendor_ruby/spring/commands/rake.rb
/usr/lib/ruby/vendor_ruby/spring/commands.rb
/usr/lib/ruby/vendor_ruby/spring/configuration.rb
/usr/lib/ruby/vendor_ruby/spring/env.rb
/usr/lib/ruby/vendor_ruby/spring/errors.rb
/usr/lib/ruby/vendor_ruby/spring/json.rb
/usr/lib/ruby/vendor_ruby/spring/process_title_updater.rb
/usr/lib/ruby/vendor_ruby/spring/server.rb
/usr/lib/ruby/vendor_ruby/spring/sid.rb
/usr/lib/ruby/vendor_ruby/spring/test/
/usr/lib/ruby/vendor_ruby/spring/test/acceptance_test.rb
/usr/lib/ruby/vendor_ruby/spring/test/application.rb
/usr/lib/ruby/vendor_ruby/spring/test/application_generator.rb
/usr/lib/ruby/vendor_ruby/spring/test/rails_version.rb
/usr/lib/ruby/vendor_ruby/spring/test/watcher_test.rb
/usr/lib/ruby/vendor_ruby/spring/test.rb
/usr/lib/ruby/vendor_ruby/spring/version.rb
/usr/lib/ruby/vendor_ruby/spring/watcher/
/usr/lib/ruby/vendor_ruby/spring/watcher/abstract.rb
/usr/lib/ruby/vendor_ruby/spring/watcher/polling.rb
/usr/lib/ruby/vendor_ruby/spring/watcher.rb