TR fails to typecheck when using optional arg and inline type specs

[jbclements]

What version of Racket are you using?

8.12.900

What program did you run?

#lang typed/racket

(define (foo3 [x : Boolean] [y : Boolean #f]) : Boolean
  (if x (foo3 #f #t) #t))

What should have happened?

I claim program should type-check...

If you got an error message, please include it here.

Type Checker: missing type for identifier;
consider adding a type annotation with `:'
identifier: foo3 in: foo3

extra info:

I suppose this is arguably a situation where following the instructions carefully solves the problem. That is, adding

(: foo3 (->* (Boolean) (Boolean) Boolean))

... to the program does allow type-checking to complete. However, this seems like a relatively unexpected failure of the type-checker, and all the more challenging because the annotation requires the use of the ->* form rather than ->.