Comment 4 for bug 1521971

Reviewed: https://review.openstack.org/268995
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=0a4249f5d1faa26b91ab5cfff5a6f5762fe7854d
Submitter: Jenkins
Branch: master

commit 0a4249f5d1faa26b91ab5cfff5a6f5762fe7854d
Author: Steven Hardy <email address hidden>
Date: Mon Jan 18 10:56:13 2016 +0000

    Fix update preview to consider type comparison

    Currently the update preview code only considers _needs_update, but
    the actual update code does a type comparison which is used to decide
    whether to attempt an in-place update vs a replacement.

    Thus, we currently erroneously say a resource is either unchanged or
    updated during update --dry-run when the type changes, but during
    the actual update we replace the resource. So instead use the same
    type comparison used during update to provide a more accurate preview.

    Change-Id: Idb2d9a55d47748007a438f84bb1f2259e553c067
    Partial-Bug: #1521971