/usr/lib/ruby/ is in ruby-devise-lastseenable 0.0.6-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/generators/
/usr/lib/ruby/vendor_ruby/generators/devise_lastseenable/
/usr/lib/ruby/vendor_ruby/generators/devise_lastseenable/devise_lastseenable_generator.rb
/usr/lib/ruby/vendor_ruby/generators/devise_lastseenable/templates/
/usr/lib/ruby/vendor_ruby/generators/devise_lastseenable/templates/migration.rb
/usr/lib/ruby/vendor_ruby/devise_lastseenable/
/usr/lib/ruby/vendor_ruby/devise_lastseenable/hooks/
/usr/lib/ruby/vendor_ruby/devise_lastseenable/hooks/lastseenable.rb
/usr/lib/ruby/vendor_ruby/devise_lastseenable/rails.rb
/usr/lib/ruby/vendor_ruby/devise_lastseenable/model.rb
/usr/lib/ruby/vendor_ruby/devise_lastseenable/version.rb
/usr/lib/ruby/vendor_ruby/devise_lastseenable.rb