/usr/lib/ruby/vendor_ruby/ is in gem2deb 0.33.1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/gem2deb/
/usr/lib/ruby/vendor_ruby/gem2deb/dh_make_ruby/
/usr/lib/ruby/vendor_ruby/gem2deb/dh_make_ruby/template/
/usr/lib/ruby/vendor_ruby/gem2deb/dh_make_ruby/template/debian/
/usr/lib/ruby/vendor_ruby/gem2deb/dh_make_ruby/template/debian/compat
/usr/lib/ruby/vendor_ruby/gem2deb/dh_make_ruby/template/debian/control
/usr/lib/ruby/vendor_ruby/gem2deb/dh_make_ruby/template/debian/copyright
/usr/lib/ruby/vendor_ruby/gem2deb/dh_make_ruby/template/debian/rules
/usr/lib/ruby/vendor_ruby/gem2deb/dh_make_ruby/template/debian/source/
/usr/lib/ruby/vendor_ruby/gem2deb/dh_make_ruby/template/debian/source/format
/usr/lib/ruby/vendor_ruby/gem2deb/dh_make_ruby/template/debian/watch
/usr/lib/ruby/vendor_ruby/gem2deb/dh_make_ruby.rb
/usr/lib/ruby/vendor_ruby/gem2deb/dh_ruby.rb
/usr/lib/ruby/vendor_ruby/gem2deb/extension_builder.rb
/usr/lib/ruby/vendor_ruby/gem2deb/gem2tgz.rb
/usr/lib/ruby/vendor_ruby/gem2deb/gem_installer.rb
/usr/lib/ruby/vendor_ruby/gem2deb/installer.rb
/usr/lib/ruby/vendor_ruby/gem2deb/make.rb
/usr/lib/ruby/vendor_ruby/gem2deb/setup_rb_installer.rb
/usr/lib/ruby/vendor_ruby/gem2deb/version.rb
/usr/lib/ruby/vendor_ruby/gem2deb.rb