tasks/datadriver.js
function(result) {
                var callback = arguments[arguments.length - 1];

                if (isLastTask && isSauceTunnelRunning) {
                    grunt.log.debug('destroy sauce tunnel if connected (once all tasks were executed)');
                    return tunnel.stop(next(callback, result));
                } else if (isLastTask && seleniumServer) {
                    grunt.log.debug('kill selenium server');
                    seleniumServer.kill();
                }

                callback(null, result);
            }
function(result) {
                var callback = arguments[arguments.length - 1];

                if (isLastTask && isSauceTunnelRunning) {
                    grunt.log.debug('destroy sauce tunnel if connected (once all tasks were executed)');
                    return tunnel.stop(next(callback, result));
                } else if (isLastTask && seleniumServer) {
                    grunt.log.debug('kill selenium server');
                    seleniumServer.kill();
                }

                callback(null, result);
            }
destroy sauce tunnel if connected (once all tasks were executed) or
kill selenium server process if created