/usr/lib/ruby/ is in ruby-molinillo 0.6.4-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/molinillo/
/usr/lib/ruby/vendor_ruby/molinillo/compatibility.rb
/usr/lib/ruby/vendor_ruby/molinillo/delegates/
/usr/lib/ruby/vendor_ruby/molinillo/delegates/resolution_state.rb
/usr/lib/ruby/vendor_ruby/molinillo/delegates/specification_provider.rb
/usr/lib/ruby/vendor_ruby/molinillo/dependency_graph/
/usr/lib/ruby/vendor_ruby/molinillo/dependency_graph/action.rb
/usr/lib/ruby/vendor_ruby/molinillo/dependency_graph/add_edge_no_circular.rb
/usr/lib/ruby/vendor_ruby/molinillo/dependency_graph/add_vertex.rb
/usr/lib/ruby/vendor_ruby/molinillo/dependency_graph/delete_edge.rb
/usr/lib/ruby/vendor_ruby/molinillo/dependency_graph/detach_vertex_named.rb
/usr/lib/ruby/vendor_ruby/molinillo/dependency_graph/log.rb
/usr/lib/ruby/vendor_ruby/molinillo/dependency_graph/set_payload.rb
/usr/lib/ruby/vendor_ruby/molinillo/dependency_graph/tag.rb
/usr/lib/ruby/vendor_ruby/molinillo/dependency_graph/vertex.rb
/usr/lib/ruby/vendor_ruby/molinillo/dependency_graph.rb
/usr/lib/ruby/vendor_ruby/molinillo/errors.rb
/usr/lib/ruby/vendor_ruby/molinillo/gem_metadata.rb
/usr/lib/ruby/vendor_ruby/molinillo/modules/
/usr/lib/ruby/vendor_ruby/molinillo/modules/specification_provider.rb
/usr/lib/ruby/vendor_ruby/molinillo/modules/ui.rb
/usr/lib/ruby/vendor_ruby/molinillo/resolution.rb
/usr/lib/ruby/vendor_ruby/molinillo/resolver.rb
/usr/lib/ruby/vendor_ruby/molinillo/state.rb
/usr/lib/ruby/vendor_ruby/molinillo.rb