image_list_detailed is called twice when launching an instance

[Akihiro Motoki]

When showing a form of launching an instance, image_list_detailed is called twice.

populate_image_id_choices and populate_instance_snapshot_id_choices both call get_available_images().
https://github.com/openstack/horizon/blob/master/openstack_dashboard/dashboards/project/instances/workflows/create_instance.py#L277

get_available_images() supports the cache of image list, but only populate_instance_snapshot_id_choices uses the cache.
It is better both methods share the cache.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/47796

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/47796
Committed: http://github.com/openstack/horizon/commit/5dedb5d5834d23771b4e378269c434d0c7f91273
Submitter: Jenkins
Branch: master

commit 5dedb5d5834d23771b4e378269c434d0c7f91273
Author: Akihiro MOTOKI <email address hidden>
Date: Mon Sep 16 05:40:24 2013 +0900

    Reduce image_list_detailed calls

    When showing a form of launching an instance, image_list_detailed is called twice.
    populate_image_id_choices and populate_instance_snapshot_id_choices both call
    get_available_images(). get_available_images() supports the cache of image list
    and it is better to share the cache by both methods.

    Closes-Bug: #1229080

    Fixes a bug that utils.get_available_images() raises a traceback
    when image_list for a project raises an exception.

    Closes-Bug: #1229083

    Add unittests for images_and_snapshots.utils to cover the above two fixes.

    Change-Id: I829a430c84e48de4faf028bdfad74b0cd8f22dc9