"Create Instance" workflow should not insert "Any Availability Zone" option in single-AZ environments

[Nicolas Simonds]

Steps to reproduce:

1. Stand up an Openstack with one Availability Zone configured
2. Open Horizon and choose "Launch Instance"

Expected behaviour:

The lone availability zone should be selected in the modal

Actual behaviour:

The option "Any Availability Zone" is selected, which is confusing because there is only one.

There is already logic to handle the case of there being 0 AZs configured, so this is in fact a subtle off-by-one error.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/48141

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/48141
Committed: http://github.com/openstack/horizon/commit/f43f11bb35f7a8290125b8398dff6daee8e38aa4
Submitter: Jenkins
Branch: master

commit f43f11bb35f7a8290125b8398dff6daee8e38aa4
Author: Nicolas Simonds <email address hidden>
Date: Tue Sep 24 13:49:36 2013 -0700

    Don't insert "Any Availaibility Zone" on single-AZ configurations

    In cases where there is one AZ configured, Horizon displays the
    option "Any Availability Zone" as the default. This is confusing,
    since there is only one.

    Since there is logic to handle the "zero AZs configured" case
    already, this is in fact an off-by-one error. Alter the logic to
    also handle the "one AZ configured" case and leave the single valid
    option selected.

    Fixes bug: 1229935

    Change-Id: I49319e9c309c1ed41fd55e9297b0b461d17c726d