/usr/lib/ruby/vendor_ruby/ is in ruby-hashery 2.1.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/hashery.rb
/usr/lib/ruby/vendor_ruby/hashery/
/usr/lib/ruby/vendor_ruby/hashery/lru_hash.rb
/usr/lib/ruby/vendor_ruby/hashery/crud_hash.rb
/usr/lib/ruby/vendor_ruby/hashery/fuzzy_hash.rb
/usr/lib/ruby/vendor_ruby/hashery/open_cascade.rb
/usr/lib/ruby/vendor_ruby/hashery/static_hash.rb
/usr/lib/ruby/vendor_ruby/hashery/key_hash.rb
/usr/lib/ruby/vendor_ruby/hashery/ordered_hash.rb
/usr/lib/ruby/vendor_ruby/hashery/casting_hash.rb
/usr/lib/ruby/vendor_ruby/hashery/core_ext.rb
/usr/lib/ruby/vendor_ruby/hashery/linked_list.rb
/usr/lib/ruby/vendor_ruby/hashery/path_hash.rb
/usr/lib/ruby/vendor_ruby/hashery/ini_hash.rb
/usr/lib/ruby/vendor_ruby/hashery/open_hash.rb
/usr/lib/ruby/vendor_ruby/hashery/query_hash.rb
/usr/lib/ruby/vendor_ruby/hashery/association.rb
/usr/lib/ruby/vendor_ruby/hashery/stash.rb
/usr/lib/ruby/vendor_ruby/hashery/property_hash.rb
/usr/lib/ruby/vendor_ruby/hashery/dictionary.rb