Zebra zserv: bogus conditional

This looks like a bug in original code from misunderstanding
of C rules of evaluation.
diff --git a/zebra/zserv.c b/zebra/zserv.c
index cb5e411..dc3d432 100644
--- a/zebra/zserv.c
+++ b/zebra/zserv.c
@@ -451,7 +451,7 @@
     }
 
   /* Metric */
-  if (cmd == ZEBRA_IPV4_ROUTE_ADD || ZEBRA_IPV6_ROUTE_ADD)
+  if (cmd == ZEBRA_IPV4_ROUTE_ADD || cmd == ZEBRA_IPV6_ROUTE_ADD)
     {
       SET_FLAG (zapi_flags, ZAPI_MESSAGE_DISTANCE);
       stream_putc (s, rib->distance);