Not able to a catch AssertionError's from within an app wrapped by supertest

gistfile1.js

var express    = require('express'),
    request    = require('supertest'),
    sinon      = require('sinon'),
    expect     = require('chai').expect;

var AssertionError = require("assert").AssertionError;

var throwAssertionErrorAndRespond = function (req, res) {
  throw new AssertionError({ message: "[2] Mocha should see this." });
  res.send('{ "success": true }');
};

var obj = {
  methodContainingSpy: undefined
};

describe("a list of failures", function () {
  var app;
  beforeEach(function () {
    app = express();
    app.get('/test', throwAssertionErrorAndRespond);
    app.get('/other-test', function (req, res) {
      res.send('{ "success": true }');
    });
  });

  it("successfully fails as Mocha can catch AssertionErrors thrown inside the test", function () {
    throw new AssertionError({ message: "[1] Mocha should see this." });
  });

  it("successfully fails as Mocha can catch AssertionErrors thrown from a function that was called", function () {
    throwAssertionErrorAndRespond();
  });

  it("successfully fails as Mocha can catch AssertionErrors thrown from the end function of supertest", function (done) {
    request(app).get('/other-test').end(function () {
      throw new AssertionError({ message: "[3] Mocha should see this." });
      done();
    });
  });

  it("Unsuccessfully fails as Mocha is unable to catch the AssertionError thrown by the app function wrapped by supertest", function (done) {
    request(app).get('/test').end(done); // THIS LOGS "[2] Mocha should see this." but doesn't fail.
  });
});

describe("using supertest and accessing state afterwards", function () {
  var app;
  beforeEach(function () {
    app = express();
    app.get('/spied-request', function (req, res) {
      if (obj.methodContainingSpy) {
        obj.methodContainingSpy();
      }
      res.send('{ "success": true }'); 
    });
  });

  it("spy is successfully accessible after spied-request is accessed from supertest", function (done) {
    var aSpy = sinon.spy();
    obj.methodContainingSpy = function () {
      aSpy();
    };

    request(app).get('/spied-request').end(function () {
      expect(aSpy.calledOnce).to.equal(true);
      done();
    });
  });
});

Turned out to be a connect.js feature - something that all web servers should do:

http://stackoverflow.com/questions/20767336/unable-to-catch-exception-from-within-a-supertest-app-request