When nested middleware is used, the `res.app` and `req.app` properties aren't restored when outerNext is called.

express-nested-server-middleware-bug.js

// In Express 1.0.8, the `res.app` and `req.app` properties aren't restored when 
// outerNext() is called by nested server middleware.
//
// Run this script, then try to visit something handled by the `notFound()` middleware 
// (e.g. `http://localhost:3000/mumble`. An assertion error is raised because `res.app`
// is equal to the `middleware()` instead of `app`.

var Assert = require('assert'),
    Express = require('express'),
    app = Express.createServer();

app.configure(function() {
  app
    .use(middleware())
    .use(app.router)
    .use(notFound());
});

function middleware() {
  var mid = Express.createServer();

  mid.get('/mid/example', function(req, res) {
    res.send('middleware here');
  });

  return mid;
}

function notFound() {
  return function(req, res, next) {
    Assert.ok(res.app === app, 'Expected main app.');
    res.send('not found', 404);
  };
}

app.get('/', function(req, res) {
  res.send('hello');
});

app.listen(3000);