/usr/lib/ is in ruby-net-irc 0.0.9-3.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/net/
/usr/lib/ruby/vendor_ruby/net/irc/
/usr/lib/ruby/vendor_ruby/net/irc/pattern.rb
/usr/lib/ruby/vendor_ruby/net/irc/message/
/usr/lib/ruby/vendor_ruby/net/irc/message/modeparser.rb
/usr/lib/ruby/vendor_ruby/net/irc/message/serverconfig.rb
/usr/lib/ruby/vendor_ruby/net/irc/server.rb
/usr/lib/ruby/vendor_ruby/net/irc/client/
/usr/lib/ruby/vendor_ruby/net/irc/client/channel_manager.rb
/usr/lib/ruby/vendor_ruby/net/irc/client.rb
/usr/lib/ruby/vendor_ruby/net/irc/message.rb
/usr/lib/ruby/vendor_ruby/net/irc/constants.rb
/usr/lib/ruby/vendor_ruby/net/irc.rb