fix date*->seconds handling of nanoseconds field

pkgs/racket-test-core/tests/racket/date.rktl

@@ -43,7 +43,7 @@
                   (date-day d) (date-month d) (date-year d)
                   (date-week-day d) (date-year-day d) (date-dst? d)
                   (date-time-zone-offset d)
-                  62500
+                  62500000
                   "MDT")]) 
   (define (test-string fmt time? result)
     (test (parameterize ([date-display-format fmt])
@@ -113,4 +113,8 @@
   (struct-copy date* (seconds->date (current-seconds))
                [hour #:parent date 5]))
 
+(let ([d ;; 2015-08-22T12:34:56.789000000Z
+       (date* 56 34 12 22 08 2015 6 233 #f 0 789000000 "UTC")])
+  (test 789/1000 - (date*->seconds d) (date->seconds d)))
+
 (report-errs)

racket/collects/racket/date.rkt

@@ -242,7 +242,7 @@
 (define (date*->seconds date [local-time? #t])
   (define s (date->seconds date local-time?))
   (if (date*? date)
-      (+ s (/ (date*-nanosecond date) 1000000))
+      (+ s (/ (date*-nanosecond date) #e1e9))
       s))
 
 (define (find-seconds sec min hour day month year [local-time? #t])