context is lost in async waterfall

[LiorRabin]

I'm trying to use continuation-local-storage module to have "currentUser" across my entire application.

When calling async waterfall the context gets lost.

		app.get('/testing/cls',
			function(req, res, next) {
				ns.run(function() {
					ns.set('currentUser', req.user._id)
			    	return next()
				})
			},
			function(req, res) {
				function fn1(cb) {
					console.log('async fn1', ns.get('currentUser'))
					return cb()
				}

				function fn2(cb) {
					console.log('async fn2', ns.get('currentUser'))
					cb()
				}

				function fn3(cb) {
					console.log('async fn3', ns.get('currentUser'))
					cb()
				}

				async.waterfall([
					fn1,
					fn2,
					fn3
				], function() {
					console.log('async waterfall done', ns.get('currentUser'))
					res.send({user: ns.get('currentUser')})
				})
			}
		)

The console prints are

27/6/2017-11:49:39 - info: (13405) - async fn1 58a1adaslkdjh32e
27/6/2017-11:49:39 - info: (13405) - async fn2
27/6/2017-11:49:39 - info: (13405) - async fn3
27/6/2017-11:49:39 - info: (13405) - async waterfall done

Fixing this problem is by wrapping ns.bind(fn2) but this means that need to change entire application code for wherever I have async.

What am I doing wrong?

Any help is appreciated :)