Description: Revert the revert of async rename
 This patch reverts https://review.openstack.org/#/c/597421/ which itself
 reverts the rename of the async keyword. Upstream did that because they
 had to maintain compat with older oslo.db.
Author: Thomas Goirand <zigo@debian.org>
Forwarded: not-needed
Last-Update: 2018-09-25

Index: nova/nova/db/sqlalchemy/api.py
===================================================================
--- nova.orig/nova/db/sqlalchemy/api.py
+++ nova/nova/db/sqlalchemy/api.py
@@ -204,7 +204,7 @@ def select_db_reader_mode(f):
         use_slave = keyed_args.get('use_slave', False)
 
         if use_slave:
-            reader_mode = get_context_manager(context).async
+            reader_mode = get_context_manager(context).async_
         else:
             reader_mode = get_context_manager(context).reader