Xcode 8.1 and Swift 3.0.1 shenanigans

When upgrading my xcode from 8.0 to 8.1 and Swift to 3.0.1, I found that I can no longer compare type with implicitly unwrapped optional in a switch statement. I need to explicitly unwrap the optional

// this no longer works
let a: String! = "asd"
let b: String = "asd"
switch a {
case b: // error: expression pattern of type 'String' cannot match values of type 'String!'
    break
default:
    break
}