Fix incorrect route for fabric configuration

Change-Id: I1e900e0ca5a949c93f5f7ffd5b9b86d1b585e367
diff --git a/scripts/nbhelper/container.py b/scripts/nbhelper/container.py
index 6e0cfcf..2f3748a 100644
--- a/scripts/nbhelper/container.py
+++ b/scripts/nbhelper/container.py
@@ -102,7 +102,7 @@
             ):
                 if prefix.reserved_ips:
                     return list(prefix.reserved_ips.values())
-            else:
+            elif not ip_addr:
                 if prefix.reserved_ips:
                     ret.extend(list(prefix.reserved_ips.values()))