Exit before post-deploy code if we are updating the plan only
Exit before post-deploy code if we are updating the plan only

This will fail if there isn't a Heat stack yet. Without a initial
create, or a stack update the following code after this flag wont do
anything.

Closes-Bug: #1644549
Change-Id: I50ac7d033b717e43609399180f92135d8be3057e

openstack/python-tripleoclient