yum fails on ecs ami

I have an instance on a public IP. This instance is running the latest ecs optimized AMI. The instance fails to run yum. It has the following error:

Loaded plugins: priorities, update-motd, upgrade-helper  
Could not retrieve mirrorlist http://repo.us-west-2.amazonaws.com/nightly/main/mirror.list error was  
14: HTTP Error 403 - Forbidden  

Even if I curl on my local computer at home:
curl -sL http://repo.us-west-2.amazonaws.com/nightly/main/mirror.list

From anywhere comes back as Forbidden. And yes, I can CURL https://www.google.com and ping 8.8.8.8 just fine on the instance itself. Just can't run yum to update and install packages.

All my ec2 linux ami's are failing to build