/usr/lib/ruby/ is in ruby-lumberjack 1.0.9-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/lumberjack/
/usr/lib/ruby/vendor_ruby/lumberjack/log_entry.rb
/usr/lib/ruby/vendor_ruby/lumberjack/formatter/
/usr/lib/ruby/vendor_ruby/lumberjack/formatter/pretty_print_formatter.rb
/usr/lib/ruby/vendor_ruby/lumberjack/formatter/exception_formatter.rb
/usr/lib/ruby/vendor_ruby/lumberjack/formatter/string_formatter.rb
/usr/lib/ruby/vendor_ruby/lumberjack/formatter/inspect_formatter.rb
/usr/lib/ruby/vendor_ruby/lumberjack/rack/
/usr/lib/ruby/vendor_ruby/lumberjack/rack/unit_of_work.rb
/usr/lib/ruby/vendor_ruby/lumberjack/template.rb
/usr/lib/ruby/vendor_ruby/lumberjack/device.rb
/usr/lib/ruby/vendor_ruby/lumberjack/formatter.rb
/usr/lib/ruby/vendor_ruby/lumberjack/logger.rb
/usr/lib/ruby/vendor_ruby/lumberjack/severity.rb
/usr/lib/ruby/vendor_ruby/lumberjack/device/
/usr/lib/ruby/vendor_ruby/lumberjack/device/size_rolling_log_file.rb
/usr/lib/ruby/vendor_ruby/lumberjack/device/rolling_log_file.rb
/usr/lib/ruby/vendor_ruby/lumberjack/device/date_rolling_log_file.rb
/usr/lib/ruby/vendor_ruby/lumberjack/device/null.rb
/usr/lib/ruby/vendor_ruby/lumberjack/device/writer.rb
/usr/lib/ruby/vendor_ruby/lumberjack/device/log_file.rb
/usr/lib/ruby/vendor_ruby/lumberjack/rack.rb
/usr/lib/ruby/vendor_ruby/lumberjack.rb