ec2-api: describe instances filter by tag should filter out the deleted tags

[MotoKen]

it works wrong when describing instances filter by a deleted tag.

# euca-describe-instances
RESERVATION r-o1oa5ya9 7dd8607e7d294efc845ccf68f8d282b7 default
INSTANCE i-00001898 ami-00000133 xxx-2 xxx-2 running 0 m1.tiny 2013-06-28T03:24:53.000Z nova monitoring-disabled 10.0.0.5 10.0.0.5 instance-store
RESERVATION r-0kvdz3qm 7dd8607e7d294efc845ccf68f8d282b7 default
INSTANCE i-00001897 ami-00000133 xxx-1 xxx-1 running 0 m1.tiny 2013-06-28T03:24:50.000Z nova monitoring-disabled 10.0.0.4 10.0.0.4 instance-store

# euca-describe-tags
TAG i-00001897 instance xxxx xxx-1
TAG i-00001898 instance xxxx xxx-2

# euca-describe-instances --filter tag:xxxx=xxx-1
RESERVATION r-0kvdz3qm 7dd8607e7d294efc845ccf68f8d282b7 default
INSTANCE i-00001897 ami-00000133 xxx-1 xxx-1 running 0 m1.tiny 2013-06-28T03:24:50.000Z nova monitoring-disabled 10.0.0.4 10.0.0.4 instance-store

# euca-delete-tags i-00001897 --tag xxxx
# euca-describe-tags
TAG i-00001898 instance xxxx xxx-2

# euca-describe-instances --filter tag:xxxx=xxx-1
RESERVATION r-0kvdz3qm 7dd8607e7d294efc845ccf68f8d282b7 default
INSTANCE i-00001897 ami-00000133 xxx-1 xxx-1 running 0 m1.tiny 2013-06-28T03:24:50.000Z nova monitoring-disabled 10.0.0.4 10.0.0.4 instance-store

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/36223

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/36289

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/36289
Committed: http://github.com/openstack/nova/commit/d73041f6082e8cb28403688e2e403fdf0cbdded2
Submitter: Jenkins
Branch: master

commit d73041f6082e8cb28403688e2e403fdf0cbdded2
Author: Sirushti Murugesan <email address hidden>
Date: Tue Jul 9 22:09:52 2013 +0530

    ec2-api: Disable describing of instances using deleted tags as filter.

    Previously, one could describe instances using a deleted tag filter
    that was once associated to the instance. The current change disables
    describing instances via a deleted tag. Also,minor refactor in the
    same function.

    fixes bug #1197242

    Change-Id: Iac6aa85b69d5a6dc563c00f3497cdab08e178ec1