Fix hierarchy in reported test failure

The hierarchy, that is the "address" of the failing test, was being
shown out of order. This fixes it so that it reflects the actual order
of nesting of test suites.

rackunit-lib/rackunit/private/format.rkt

@@ -44,7 +44,9 @@
 (define (combine-names test-name suite-names)
   (define any-names? (or test-name (not (empty? suite-names))))
   (and any-names?
-       (string-join (snoc (or test-name "Unnamed test") suite-names) " > ")))
+       (string-join (snoc (or test-name "Unnamed test")
+                          (reverse suite-names))
+                    " > ")))
 
 (define (snoc v vs) (append vs (list v)))