Merge remote-tracking branch 'origin/swift-4.0-branch' into stable

* origin/swift-4.0-branch:
  Merging r294800: ------------------------------------------------------------------------ r294800 | gbiv | 2017-02-10 14:52:29 -0800 (Fri, 10 Feb 2017) | 10 lines
  Merging r294855: ------------------------------------------------------------------------ r294855 | compnerd | 2017-02-11 09:24:09 -0800 (Sat, 11 Feb 2017) | 3 lines