[Swift CI] Build Failure: 2. Swift Source Compatibility Suite (master) #220

Any ideas?
It looks like we can’t find UICollectionViewLayout.prepare(), but the same file compiled okay in the “Chatto” project (this one is “ChattoApp”). The SDK versions appear to be the same as the previous build, and Doug’s commit looks unrelated to me. The project is using the same hash as the previous build too.
ChatCollectionViewLayout.swift:86:24: error: method does not override any method from its superclass
    open override func prepare() {
         ~~~~~~~~ ^
ChatCollectionViewLayout.swift:87:15: error: cannot invoke 'prepare' with no arguments
ChatCollectionViewLayout.swift:87:15: note: overloads for 'prepare' exist with these partially matching parameter lists: (forCollectionViewUpdates: [UICollectionViewUpdateItem]), (forAnimatedBoundsChange: CGRect)
rdar://problem/34395450 <rdar://problem/34395450>


On Sep 12, 2017, at 12:40 PM, no-reply@swift.org wrote:

[FAILURE] swift-master-source-compat-suite [#220]

Build URL: https://ci.swift.org/job/swift-master-source-compat-suite/220/
Project: swift-master-source-compat-suite
Date of build: Tue, 12 Sep 2017 12:00:32 -0500
Build duration: 2 hr 41 min


Commit 7dc8737c9c46e5d0c54fe36415e2fd8ed12b5dac by dgregor:
[Sequence] Make Sequence.SubSequence conform to Sequence.

edit: stdlib/private/StdlibCollectionUnittest/CheckSequenceType.swift
edit: stdlib/public/core/ExistentialCollection.swift.gyb
edit: stdlib/public/core/SequenceWrapper.swift
edit: stdlib/public/core/Collection.swift
edit: stdlib/private/StdlibUnittest/StdlibUnittest.swift.gyb
edit: stdlib/public/core/Sequence.swift