The Swift 4.2.0 release is now in final convergence. This means the release will only take critical changes at this point. If there is a change you need to take, please email or direct message me.
Convergence snapshots can be found here:
swift-4.2-branch is now open take changes that aren't critical for 4.2.0 but are considered worth pulling in for a potential 4.2.1 release at some point in the future. These changes will not go into 4.2.0 unless specifically requested (see above).