Make the code that says what the effect of a failed check is a tiny bit clearer.

svn: r15970

collects/test-engine/scheme-tests.ss

@@ -220,7 +220,9 @@
                           (list (maker src (test-format) test-val expect range) test-val #f)])))])
     (cond [(check-fail? result)
            (send (send test-info get-info) check-failed result (check-fail-src result) exn)
-           (when exn (raise exn))]
+           (if exn
+	       (raise exn)
+	       #f)]
           [else
            #t])))