Comment 15 for bug 1508115

Reviewed: https://review.openstack.org/246614
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=67e9b5bf1131019ed0746fde7e56c60462327c53
Submitter: Jenkins
Branch: stable/kilo

commit 67e9b5bf1131019ed0746fde7e56c60462327c53
Author: Steven Hardy <email address hidden>
Date: Wed Oct 21 18:56:01 2015 +0100

    Allow in-place updates for all compatible types

    We previously only allowed a resource to update in-place when the 'type'
    field in the old and new templates matched. In an age of environment type
    mappings, this is incorrect. Instead, allow a resource to be updated
    in-place when the old and new resource plugins are of the same class, since
    this is actually what determines whether handle_update is capable of
    correctly updating the resource in-place.

    There is a special-case for TemplateResource as we currently subclass it
    for each template type, but all TemplateResource subclasses are in fact
    capable of converting between each other via a stack update.

    Change-Id: Iba4abf5efd9737ca6a17d8c91d5c54ab6d3f12e0
    Co-Authored-By: Zane Bitter <email address hidden>
    Closes-Bug: #1508115
    (cherry picked from commit 98044dbd17c703e6062752f043e1cac6563e3589)