[2905] updated lettuce tests to reflect the rcode change to SERVFAIL

tests/lettuce/features/auth_badzone.feature

@@ -2,7 +2,7 @@ Feature: Authoritative DNS server with a bad zone
     This feature set is for testing the execution of the b10-auth
     component when one zone is broken, whereas others are fine. In this
     case, b10-auth should not reject the data source, but reject the bad
-    zone only and serve the good zones anyway.
+    zone only (with SERVFAIL) and serve the good zones anyway.
 
     Scenario: Bad zone
         Given I have bind10 running with configuration auth/auth_badzone.config
@@ -44,6 +44,6 @@ Feature: Authoritative DNS server with a bad zone
         ns2.example.org.        3600    IN      A       192.0.2.4
         """
 
-        A query for www.example.com should have rcode REFUSED
-        A query for www.example.net should have rcode REFUSED
-        A query for www.example.info should have rcode REFUSED
+        A query for www.example.com should have rcode SERVFAIL
+        A query for www.example.net should have rcode SERVFAIL
+        A query for www.example.info should have rcode SERVFAIL