Saggitarius 0.6.9 で変なメッセージが出る

test.scm

(import (rnrs) (rfc http) (rfc base64))

(define (basic-auth-string user password)
  (string-append "Basic "
                 (base64-encode-string (string-append user ":" password))))

(define (access)
  (receive (status header body)
      (http-get "htaccess.cman.jp"
                "/sample_go/basic/"
                :secure #t
                :authorization (basic-auth-string "guest" "password"))
    body))

(display (access))