/usr/lib/ is in ruby-em-synchrony 1.0.3-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/em-synchrony/amqp.rb
/usr/lib/ruby/
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/active_record/
/usr/lib/ruby/vendor_ruby/active_record/connection_adapters/
/usr/lib/ruby/vendor_ruby/active_record/connection_adapters/em_mysql2_adapter.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/
/usr/lib/ruby/vendor_ruby/em-synchrony/em-remcached.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/activerecord.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/mongo.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/iterator.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/em-jack.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/fiber_iterator.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/thread.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/em-redis.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/keyboard.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/mongoid.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/em-hiredis.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/tcpsocket.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/em-http.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/mysql2.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/connection_pool.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/core_ext.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/em-multi.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/em-memcache.rb
/usr/lib/ruby/vendor_ruby/em-synchrony/em-mongo.rb
/usr/lib/ruby/vendor_ruby/em-synchrony.rb