Comment 40 for bug 1224828

Reviewed: https://review.openstack.org/154619
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=fa6251de0d9dccd133b439cdafd69c4e0664be6b
Submitter: Jenkins
Branch: master

commit fa6251de0d9dccd133b439cdafd69c4e0664be6b
Author: Steven Hardy <email address hidden>
Date: Wed Jul 22 19:04:11 2015 +0100

    Reuse existing environment on PATCH update

    Extend the "existing" option to the engine update so we reuse
    all of the environment, not only the parameters, which means
    that when -x is specified during a stack-update we'll maintain
    any existing resource_registry (and files), then merge any
    environment passed during the update into those existing.

    This allows the users to optionally omit the environment when
    performing a stack update, which is particularly convenient
    if you're updating a stack which has a large or complex
    environment.

    Co-Authored-By: Ton Ngo <email address hidden>
    Partial-Bug: 1224828
    Change-Id: I3033063a06c3913a1ae89ea1ec1fdac688ebd2cf