corret c98b0e6 so that empty? is not provided by racket/base

also do the same treatment with cons? as with empty?

racket/collects/racket/contract/private/helpers.rkt

@@ -13,9 +13,10 @@
 
 (require setup/main-collects
          racket/struct-info
-         (only-in racket/private/list empty?)
+         (only-in racket/private/list-predicates empty? cons?)
          (for-template racket/base
-                       (only-in racket/private/list empty?)))
+                       (only-in racket/private/list-predicates
+                                empty? cons?)))
 
 (define (update-loc stx loc)
   (datum->syntax stx (syntax-e stx) loc))
@@ -191,7 +192,7 @@
              string<=?
              #:key symbol->string)))
 
--- also add empty? to the above
+-- also add empty? and cons? to the above
 
 |#
 
@@ -370,8 +371,9 @@
          (weak-box? . #t)
          (will-executor? . #t)
          (zero? . #t)
-         ;; from racket/private/list
-         (empty? . #t)))
+         ;; from racket/private/list-predicates
+         (empty? . #t)
+         (cons? . #t)))
 
 (define (known-good-contract? id)
   (define r-id (syntax-e id))

racket/collects/racket/list.rkt

@@ -62,7 +62,7 @@
          remf*)
 
 (require (for-syntax racket/base)
-         (only-in racket/private/list empty?))
+         "private/list-predicates.rkt")
 
 (define (first x)
   (if (and (pair? x) (list? x))
@@ -112,7 +112,6 @@
     (cdr l)
     (raise-argument-error 'rest "(and/c list? (not/c empty?))" l)))
 
-(define (cons? l) (pair? l))
 (define empty '())
 
 (define (make-list n x)

racket/collects/racket/private/list-predicates.rkt

@@ -0,0 +1,6 @@
+#lang racket/base
+
+(provide empty? cons?)
+
+(define (empty? l) (null? l))
+(define (cons? l) (pair? l))

racket/collects/racket/private/list.rkt

@@ -30,11 +30,7 @@
            reverse
 
            compose
-           compose1
-
-           empty?)
-
-  (define (empty? l) (null? l))
+           compose1)
 
   (#%require (rename "sort.rkt" raw-sort sort)
              (for-syntax "stxcase-scheme.rkt")