Empty template throws error in 2.2.1

Using jQuery 1.9.0 and Knockout 2.2.1, changing the dynamic template name to null throws an error: 

Uncaught TypeError: Cannot read property 'length' of null 

on line 3008.

see this fiddle to reproduce the issue: http://jsfiddle.net/NtKCJ/9/


(this works fine in Knockout 2.2.0)