define-predicate doesn't work for union type that contains (List Any) type.

What version of Racket are you using?

v7.8

What program did you run?

#lang typed/racket

(define-type Foo (List Any))
(define-predicate foo? Foo)

(define-type Bar-List (Listof Bar))
(define-type Bar (U Foo Bar-List))

(define-predicate bar-list? Bar-List)
(define-predicate bar? Bar)

(displayln (bar? '((1) ((2)) (((3))))))

What should have happened?

#t

It works if we define bar? manually:

(define-predicate bar-list? Bar-List)
(: bar? [-> Any Boolean : Bar])
(define bar?
  (λ (arg)
    (or (foo? arg)
        (bar-list? arg))))

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

Type Checker: Type Bar could not be converted to a predicate: required a flat contract but generated a chaperone contract
  in: Bar

Start by running the supplied Typed Racket program with v7.8 and inspect the define-predicate entry point for unions containing (List Any). Determine why Bar cannot be converted to a flat contract. Done means the example produces #t and regression coverage verifies the behavior.