Should tearDown be queued on process.nextTick?

I've encountered an issue that's reproducible with async.parallel/auto and nodeunit.

``` javascript
var async = require('async');
var str;

exports.setUp = function(cb){
console.log('setup');
str = "This is a test";
cb();
}

exports.tearDown = function(cb){
//process.nextTick(function(){
console.log('teardown');
str = undefined;
cb();
//});
}

exports["testA"] = function(test){
async.auto({
test1:function(cb, results){
console.log('test1');
cb(new Error("test"));
},
test2:function(cb, results){
console.log('test2');
console.log(str, str.length);
cb();
}
}, function(err, results){
if(err) console.error(err);
test.done();
});
}

exports["testB"] = function(test){
async.parallel({
test1:function(cb, results){
console.log('test1');
cb(new Error("test"));
},
test2:function(cb, results){
console.log('test2');
console.log(str, str.length);
cb();
}
}, function(err, results){
if(err) console.error(err);
test.done();
});
}
```

This produces the output:

> setup
> test1
> [Error: test]
> teardown
> test2
> teardown
> ✖ testA
>
> TypeError: Cannot read property 'length' of undefined
> at Array.exports.testA.async.auto.test2 [as 0](/Users/davefenster/temp/testnodeunitbug/test.js:26:24)
> at async.auto (/Users/davefenster/node_modules/async/lib/async.js:406:38)
> at Array.forEach (native)
> at _forEach (/Users/davefenster/node_modules/async/lib/async.js:26:24)
> at Object.async.auto (/Users/davefenster/node_modules/async/lib/async.js:382:9)
> at Object.exports.testA (/Users/davefenster/temp/testnodeunitbug/test.js:19:8)
> at wrapTest (/Users/davefenster/node_modules/nodeunit/lib/core.js:231:20)
> at _asyncMap (/Users/davefenster/node_modules/nodeunit/deps/async.js:163:13)
> at async.forEachSeries.iterate (/Users/davefenster/node_modules/nodeunit/deps/async.js:126:25)
> at _asyncMap (/Users/davefenster/node_modules/nodeunit/deps/async.js:160:17)
>
> setup
> test1
> [Error: test]
> teardown
> test2
> teardown
> ✖ testA
>
> TypeError: Cannot read property 'length' of undefined
> at Array.exports.testA.async.auto.test2 [as 0](/Users/davefenster/temp/testnodeunitbug/test.js:26:24)
> at async.auto (/Users/davefenster/node_modules/async/lib/async.js:406:38)
> at Array.forEach (native)
> at _forEach (/Users/davefenster/node_modules/async/lib/async.js:26:24)
> at Object.async.auto (/Users/davefenster/node_modules/async/lib/async.js:382:9)
> at Object.exports.testA (/Users/davefenster/temp/testnodeunitbug/test.js:19:8)
> at wrapTest (/Users/davefenster/node_modules/nodeunit/lib/core.js:231:20)
> at _asyncMap (/Users/davefenster/node_modules/nodeunit/deps/async.js:163:13)
> at async.forEachSeries.iterate (/Users/davefenster/node_modules/nodeunit/deps/async.js:126:25)
> at _asyncMap (/Users/davefenster/node_modules/nodeunit/deps/async.js:160:17)
>
> FAILURES: 2/2 assertions failed (12ms)
>
> FAILURES: Undone tests (or their setups/teardowns):
> - testB
>
> To fix this, make sure all tests call test.done()

The error manifests itself because tearDown runs before all the async.auto and async.parallel functions have executed. Ideally, what I'd want is the tearDown to run only after async.auto/parallel are complete.
To make the tests pass, uncomment the process.nextTick line in the tearDown function.

Should nodeunit be putting tearDown on the nextTick queue all the time?

Reproduce the issue with the async.auto and async.parallel fixtures shown in the report, then inspect nodeunit/lib/core.js around wrapTest and its teardown handling. Verify the ordering of tearDown relative to asynchronous callbacks, and confirm that the completed tests no longer access cleaned-up state before teardown finishes.

Written by the indexing model from the issue text.