Fixing repo init to check out Chromium OS code

Building Chromium OS is a little tricky. Although the instructions from the project page are pretty detailed, one bump I ran into was this error when I put in the "repo init ..." command:

fatal: Cannot get https://chromium.googlesource.com/a/external/repo.git/clone.bundle
fatal: HTTP error 401

Turns out that there's an issue with in the repo init code that makes it fail if there's anything wrong with your ~/.netrc file. My system didn't even have a .netrc file, which made it hard to know how to fix that problem.