Cancelling a KSPromise doesn't notify promises chained on it that the underlying promise has been cancelled

For Example:
With KSPromises chained as follows:
promise3 --> promise2 --> promise1

If [promise2 cancel] is called, promise1 is also told to cancel, but promise 3 is never notified that the chain has been cancelled and is left in a state it cannot recover from on its own.
