use DEVELOPMENT-SNAPSHOT-2019-01-28-a
use DEVELOPMENT-SNAPSHOT-2019-01-28-a

Motivation:

New Swift versions are great.

Modifications:

Upgrade to 5.0-DEVELOPMENT-SNAPSHOT-2019-01-28-a.

Result:

Should unblock #769.

apple/swift-nio,apple/swift-nio,apple/swift-nio,apple/swift-nio,apple/swift-nio