Fixed a bug in find-base-cases.

svn: r13303

collects/redex/private/rg-test.ss

@@ -48,6 +48,13 @@
           (v . (2 0)) (v-e . (2 2 2 2 1)) (v-v . (0 2))
           (x . (0)) (x-e . (2 2 2 2 1 3)) (x-v . (2 2)) (x-x . (0)))))
 
+(let ()
+  (define-language L
+    (x (variable-prefix x)
+       (variable-except y))
+    (y y))
+  (test (hash-ref (find-base-cases L) 'x) '(0 0)))
+
 (let ()
   (define-language lang
     (e number x y)

collects/redex/private/rg.ss

@@ -429,6 +429,8 @@ To do a better job of not generating programs with free variables,
              (set! nts (cons (symbol->nt pat) nts)))]
           [`(cross ,(? symbol? x-nt))
            (set! nts (cons x-nt nts))]
+          [`(variable-except ,s ...) (void)]
+          [`(variable-prefix ,p) (void)]
           [`() (void)]
           [(struct ellipsis (_ p _ _))
            (loop p)]