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 locking master while we land some source changes in support of the updated SDKs on both master and the swift-3.0-preview-5-branch. 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. The latest Xcode 8 beta can be downloaded at: https://developer.apple.com/download/