fix meta/salt with missing pillar

Change-Id: I57c2c381c209d31868c7ba651be175b2639e3d7c
diff --git a/keystone/meta/salt.yml b/keystone/meta/salt.yml
index 7246158..386a2f1 100644
--- a/keystone/meta/salt.yml
+++ b/keystone/meta/salt.yml
@@ -8,7 +8,7 @@
     priority: 520
 
 minion:
-  {%- if pillar.keystone.server is defined or pillar.keystone.client is defined %}
+  {%- if pillar.get('keystone', {}).get('server') or pillar.get('keystone', {}).get('client') %}
     {%- from "keystone/map.jinja" import server with context %}
     {%- from "keystone/map.jinja" import client with context %}