[racket] rename-transformer-target, prop:rename-transformer, and contracts

If I have this program:
#lang racket/base

(module foo racket/base
  (require racket/contract/base)
  (struct foo (id) #:transparent
    #:property prop:rename-transformer (struct-field-index id))
  (provide (contract-out
            [struct foo ([id identifier?])])))
(require 'foo)

(define id #'x)
(rename-transformer-target (foo id))

Then it will return this:
#<syntax ?>
Instead of returning id.  

Is this a bug?

Why wouldn’t this work?

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