Let the config repository shadow another one

Change-Id: I95bd35e13739d29644565ddb0c5f7866bcafac72
diff --git a/resources/_internal.yaml b/resources/_internal.yaml
index 4cb002f..7b90f43 100644
--- a/resources/_internal.yaml
+++ b/resources/_internal.yaml
@@ -26,6 +26,7 @@
         - config:
             zuul/config-project: True
             zuul/shadow:
+              - openstack/devstack
               - openstack/openstack-zuul-jobs
         - sf-jobs
         - zuul/zuul-jobs: