Tomorrow we will be temporarily bringing down the CI, starting around 2 PM, California time, in order to upgrade to the latest beta of Xcode 8 and the associated SDKs. We will also be tagging and applying some source changes in support of the updated SDKs. We expect the upgrade process to take several hours. We’ll send out a message when the upgrade is complete.
As a reminder, once the upgrade is complete, if you are doing development on a Mac, the minimum required Xcode to build Swift from source will be the latest Xcode 8 beta — in this case, Xcode 8 GM seed. It can be downloaded at: https://developer.apple.com/download/