/usr/lib/ruby/ is in ruby-sprite-factory 1.7.1-2.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/sprite_factory.rb
/usr/lib/ruby/vendor_ruby/sprite_factory/
/usr/lib/ruby/vendor_ruby/sprite_factory/runner.rb
/usr/lib/ruby/vendor_ruby/sprite_factory/layout/
/usr/lib/ruby/vendor_ruby/sprite_factory/layout/vertical.rb
/usr/lib/ruby/vendor_ruby/sprite_factory/layout/packed.rb
/usr/lib/ruby/vendor_ruby/sprite_factory/layout/horizontal.rb
/usr/lib/ruby/vendor_ruby/sprite_factory/style.rb
/usr/lib/ruby/vendor_ruby/sprite_factory/library/
/usr/lib/ruby/vendor_ruby/sprite_factory/library/image_magick.rb
/usr/lib/ruby/vendor_ruby/sprite_factory/library/rmagick.rb
/usr/lib/ruby/vendor_ruby/sprite_factory/library/chunky_png.rb