/usr/lib/ruby/ is in ruby-eventmachine 1.0.7-3build3.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/em/
/usr/lib/ruby/vendor_ruby/em/threaded_resource.rb
/usr/lib/ruby/vendor_ruby/em/spawnable.rb
/usr/lib/ruby/vendor_ruby/em/deferrable/
/usr/lib/ruby/vendor_ruby/em/deferrable/pool.rb
/usr/lib/ruby/vendor_ruby/em/pool.rb
/usr/lib/ruby/vendor_ruby/em/streamer.rb
/usr/lib/ruby/vendor_ruby/em/processes.rb
/usr/lib/ruby/vendor_ruby/em/future.rb
/usr/lib/ruby/vendor_ruby/em/file_watch.rb
/usr/lib/ruby/vendor_ruby/em/connection.rb
/usr/lib/ruby/vendor_ruby/em/completion.rb
/usr/lib/ruby/vendor_ruby/em/process_watch.rb
/usr/lib/ruby/vendor_ruby/em/protocols.rb
/usr/lib/ruby/vendor_ruby/em/protocols/
/usr/lib/ruby/vendor_ruby/em/protocols/smtpserver.rb
/usr/lib/ruby/vendor_ruby/em/protocols/socks4.rb
/usr/lib/ruby/vendor_ruby/em/protocols/postgres3.rb
/usr/lib/ruby/vendor_ruby/em/protocols/header_and_content.rb
/usr/lib/ruby/vendor_ruby/em/protocols/line_and_text.rb
/usr/lib/ruby/vendor_ruby/em/protocols/saslauth.rb
/usr/lib/ruby/vendor_ruby/em/protocols/httpclient2.rb
/usr/lib/ruby/vendor_ruby/em/protocols/smtpclient.rb
/usr/lib/ruby/vendor_ruby/em/protocols/stomp.rb
/usr/lib/ruby/vendor_ruby/em/protocols/httpclient.rb
/usr/lib/ruby/vendor_ruby/em/protocols/memcache.rb
/usr/lib/ruby/vendor_ruby/em/protocols/object_protocol.rb
/usr/lib/ruby/vendor_ruby/em/protocols/tcptest.rb
/usr/lib/ruby/vendor_ruby/em/protocols/line_protocol.rb
/usr/lib/ruby/vendor_ruby/em/protocols/linetext2.rb
/usr/lib/ruby/vendor_ruby/em/pure_ruby.rb
/usr/lib/ruby/vendor_ruby/em/tick_loop.rb
/usr/lib/ruby/vendor_ruby/em/resolver.rb
/usr/lib/ruby/vendor_ruby/em/queue.rb
/usr/lib/ruby/vendor_ruby/em/messages.rb
/usr/lib/ruby/vendor_ruby/em/deferrable.rb
/usr/lib/ruby/vendor_ruby/em/timers.rb
/usr/lib/ruby/vendor_ruby/em/channel.rb
/usr/lib/ruby/vendor_ruby/em/version.rb
/usr/lib/ruby/vendor_ruby/em/iterator.rb
/usr/lib/ruby/vendor_ruby/em/callback.rb
/usr/lib/ruby/vendor_ruby/em/buftok.rb
/usr/lib/ruby/vendor_ruby/jeventmachine.rb
/usr/lib/ruby/vendor_ruby/eventmachine.rb