Subject: Why does git checkout -b touch the index?

From: David Turner <[email-masked]>
Date: Fri, 14 Oct 2016 10:35:56 -0400

If I do "git checkout -b fleem", with no additional flags, why does it
need to rewrite the index?  Or even read the index? 

(this is kind of a bug report, I guess, but it's a pretty minor bug that
I only noticed because I was out of hard drive space)