Fix typo in function name

src/preupg/list-rules/test

@@ -108,7 +108,7 @@ xcase__test() {
 }
 
 xcase__diag() {
-    dump__file preupg.out preupg.out.filtered preupg.err
+    jat_dump__file preupg.out preupg.out.filtered preupg.err
 }
 
 xcase__cleanup() {