Swift.org will stop providing new Ubuntu 16.10 toolchain starting Monday, Aug 27th, 2018 for master and swift-4.2-branch now that 18.04 is supported.
Do you need to remove Ubuntu 16.10 from the Requirements and/or Supported Target Platforms?
The Continuous Integration page also needs an update.
(See "macOS 10.12.5", "Xcode 9 beta 2", "Ubuntu 16.10", etc.)
@benrimmington Thanks for bringing this to our attention, I have updated the website with new information.