The link in Lab 2, Task 2, step 4 appears to be broken:
Thank you for the comment. Indeed the file, and all reference to it is gone from openstack.org and devstack.org. I'm not sure why or where it may pop up. I've looked the places I would think it would be as well as using search engines. It appears to be gone.
With Open Source projects it is difficult to know if this was intentional, so as to not have to maintain a guide on a quickly changing file, or unintentional and it will be rebuilt. The installation of DevStack has changed more than usual with the recent release. The previous guide was aging. If I find it or it returns to the site I will update a comment here.