Tighten up a test case. NFC.
Tighten up a test case. NFC.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@313098 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit 8beeb68a1f51274a0ec7e628875d4722c8f81aba)

apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang