Change user short name

I've seen several instructions on how to change the user short name including an Apple Knowledgebase document, but none of it works for me so I'm thinking there is something else going on here.

I installed a new hard drive and installed Mountain Lion on it. In the setup, I created a user using the same name and short name as my previous user (short name is scott). I logged in and restored all my files using Migration Assistant from a Time Machine backup. I can't remember exactly what happened next, but there was a conflict being that my current user and my old user that I was importing had the same name, so I had to rename the short name as scott1. I logged in as scott1, which was the user account I was using prior to the new hard drive. I then deleted the account I setup after the new install, scott.

So, I'd like to change scott1 to scott. I login as root and change the user folder name from scott1 to scott. I then open Users and Groups to create a new account with short name scott. It will not allow this and says "this user name already exists". The scott account was deleted and I can find no remnants of it in the users folder, but I'm unable to create it.

Any ideas or work arounds? I could live with it, but I'm already starting to run into problems where some applications are looking for the scott folder and can't find it, because that's how it was setup on my old hard drive.