Updated openstack/openstack
Project: openstack/oslo.db  a7b3522477356d5bdf25294f41f7b3090648d4d6

Create a nested helper function that will work on py3.x

The contextlib.nested function doesn't exist on py3.x so
in order to retain similar functionality create an equivalent
that will perform good enough for oslo.db usage.

Change-Id: I326816c9301f1c625e1e2723d4d639fd81cc596c