Fix KeyError for acl put

Change-Id: I4ed856663ee0f560bc2bf98a5d5fc8d73475fae1
Related-PROD: PROD-25719
diff --git a/_states/barbicanv1.py b/_states/barbicanv1.py
index af202d5..493f52a 100644
--- a/_states/barbicanv1.py
+++ b/_states/barbicanv1.py
@@ -237,7 +237,7 @@
 
     missing_users = [user_id
                      for user_id in kwargs.get('users', [])
-                     if user_id not in resp['read']['users']]
+                     if user_id not in resp['read'].get('users', [])]
     if missing_users:
         kwargs['users'] = missing_users
         resp = _barbicanv1_call('secret_acl_put', name=name,