[5.9] Downgrade priors version mismatch warning#1398

keith wants to merge 1 commit intorelease/5.9swiftlang/swift-driver:release/5.9from

ks/5.9-downgrade-priors-version-mismatch-warningswiftlang/swift-driver:ks/5.9-downgrade-priors-version-mismatch-warningCopy head branch name to clipboard