Streams are painful

streams.js

function existsAsync(id) {
    var deferred = Q.defer();
    var clientRequest = knoxClient.head(id);

    clientRequest.on("error", deferred.reject);
    clientRequest.on("response", function (clientResponse) {
        function onEnd() {
            cleanup();
            deferred.resolve(clientResponse.statusCode === 200);
        }
        
        function onError(error) {
            cleanup();
            deferred.reject(error);
        }

        function cleanup() {
            clientResponse.removeListener("end", onEnd);
            clientResponse.removeListener("error", onError);
        }

        clientResponse.on("end", onEnd);
        clientResponse.on("error", onError);
    });


    return deferred.promise;
};