/usr/lib/ is in ruby-mongo 1.10.0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/
/usr/lib/ruby/vendor_ruby/
/usr/lib/ruby/vendor_ruby/mongo/
/usr/lib/ruby/vendor_ruby/mongo/exception.rb
/usr/lib/ruby/vendor_ruby/mongo/legacy.rb
/usr/lib/ruby/vendor_ruby/mongo/mongo_sharded_client.rb
/usr/lib/ruby/vendor_ruby/mongo/gridfs.rb
/usr/lib/ruby/vendor_ruby/mongo/cursor.rb
/usr/lib/ruby/vendor_ruby/mongo/utils/
/usr/lib/ruby/vendor_ruby/mongo/utils/thread_local_variable_manager.rb
/usr/lib/ruby/vendor_ruby/mongo/utils/core_ext.rb
/usr/lib/ruby/vendor_ruby/mongo/utils/conversions.rb
/usr/lib/ruby/vendor_ruby/mongo/utils/support.rb
/usr/lib/ruby/vendor_ruby/mongo/utils/server_version.rb
/usr/lib/ruby/vendor_ruby/mongo/gridfs/
/usr/lib/ruby/vendor_ruby/mongo/gridfs/grid_ext.rb
/usr/lib/ruby/vendor_ruby/mongo/gridfs/grid_io.rb
/usr/lib/ruby/vendor_ruby/mongo/gridfs/grid_file_system.rb
/usr/lib/ruby/vendor_ruby/mongo/gridfs/grid.rb
/usr/lib/ruby/vendor_ruby/mongo/bulk_write_collection_view.rb
/usr/lib/ruby/vendor_ruby/mongo/functional.rb
/usr/lib/ruby/vendor_ruby/mongo/utils.rb
/usr/lib/ruby/vendor_ruby/mongo/mongo_replica_set_client.rb
/usr/lib/ruby/vendor_ruby/mongo/collection.rb
/usr/lib/ruby/vendor_ruby/mongo/db.rb
/usr/lib/ruby/vendor_ruby/mongo/connection.rb
/usr/lib/ruby/vendor_ruby/mongo/collection_writer.rb
/usr/lib/ruby/vendor_ruby/mongo/mongo_client.rb
/usr/lib/ruby/vendor_ruby/mongo/functional/
/usr/lib/ruby/vendor_ruby/mongo/functional/read_preference.rb
/usr/lib/ruby/vendor_ruby/mongo/functional/authentication.rb
/usr/lib/ruby/vendor_ruby/mongo/functional/uri_parser.rb
/usr/lib/ruby/vendor_ruby/mongo/functional/logging.rb
/usr/lib/ruby/vendor_ruby/mongo/functional/write_concern.rb
/usr/lib/ruby/vendor_ruby/mongo/functional/sasl_java.rb
/usr/lib/ruby/vendor_ruby/mongo/connection/
/usr/lib/ruby/vendor_ruby/mongo/connection/node.rb
/usr/lib/ruby/vendor_ruby/mongo/connection/socket.rb
/usr/lib/ruby/vendor_ruby/mongo/connection/socket/
/usr/lib/ruby/vendor_ruby/mongo/connection/socket/socket_util.rb
/usr/lib/ruby/vendor_ruby/mongo/connection/socket/tcp_socket.rb
/usr/lib/ruby/vendor_ruby/mongo/connection/socket/ssl_socket.rb
/usr/lib/ruby/vendor_ruby/mongo/connection/socket/unix_socket.rb
/usr/lib/ruby/vendor_ruby/mongo/connection/pool.rb
/usr/lib/ruby/vendor_ruby/mongo/connection/pool_manager.rb
/usr/lib/ruby/vendor_ruby/mongo/connection/sharding_pool_manager.rb
/usr/lib/ruby/vendor_ruby/mongo/networking.rb
/usr/lib/ruby/vendor_ruby/mongo.rb