/usr/lib/ruby/ is in ruby-foreigner 1.4.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/foreigner/
/usr/lib/ruby/vendor_ruby/foreigner.rb
/usr/lib/ruby/vendor_ruby/foreigner/adapter.rb
/usr/lib/ruby/vendor_ruby/foreigner/connection_adapters/
/usr/lib/ruby/vendor_ruby/foreigner/connection_adapters/abstract/
/usr/lib/ruby/vendor_ruby/foreigner/connection_adapters/abstract/foreign_key_definition.rb
/usr/lib/ruby/vendor_ruby/foreigner/connection_adapters/abstract/schema_definitions.rb
/usr/lib/ruby/vendor_ruby/foreigner/connection_adapters/abstract/schema_statements.rb
/usr/lib/ruby/vendor_ruby/foreigner/connection_adapters/abstract/table.rb
/usr/lib/ruby/vendor_ruby/foreigner/connection_adapters/abstract/table_definition.rb
/usr/lib/ruby/vendor_ruby/foreigner/connection_adapters/mysql2_adapter.rb
/usr/lib/ruby/vendor_ruby/foreigner/connection_adapters/mysql_adapter.rb
/usr/lib/ruby/vendor_ruby/foreigner/connection_adapters/noop_adapter.rb
/usr/lib/ruby/vendor_ruby/foreigner/connection_adapters/postgresql_adapter.rb
/usr/lib/ruby/vendor_ruby/foreigner/connection_adapters/sql2003.rb
/usr/lib/ruby/vendor_ruby/foreigner/loader.rb
/usr/lib/ruby/vendor_ruby/foreigner/migration/
/usr/lib/ruby/vendor_ruby/foreigner/migration/command_recorder.rb
/usr/lib/ruby/vendor_ruby/foreigner/railtie.rb
/usr/lib/ruby/vendor_ruby/foreigner/schema_dumper.rb