[plugins]Deploy stucks when changing compatible releases and updating plugin

[Alexander Kurenyshev]

Steps to reproduce:
1) Deploy Fuel 6.1
2) Create plugin which support 6.1 Fuel release:
Cut of metadata.yaml output:
releases:
  - os: ubuntu
    version: 2014.2.1-6.1
    mode: ['ha', 'multinode']
    deployment_scripts_path: deployment_scripts/
    repository_path: repositories/ubuntu
  - os: centos
    version: 2014.2.1-6.1
    mode: ['ha', 'multinode']
    deployment_scripts_path: deployment_scripts/
    repository_path: repositories/centos

3) Install plugin
4) Create new environment and enable plugin at the UI
4) Modify plugin: increase plugin version, change supported release to 6.0 (make plugin unsupported in current installation)
5) Install plugin
6) Deploy cluster

Observed behaviour:
Deploy stucks, below at the astute logs:
[7f0f5cd2f740] (manager) Traceback (most recent call last):
  File "/usr/lib/python2.6/site-packages/nailgun/task/manager.py", line 54, in _call_silently
    to_return = method(task, *args, **kwargs)
  File "/usr/lib/python2.6/site-packages/nailgun/task/task.py", line 166, in message
    orchestrator_graph, task.cluster, nodes)
  File "/usr/lib/python2.6/site-packages/nailgun/orchestrator/stages.py", line 46, in pre_deployment_serialize
    graph_tasks, cluster, nodes)
  File "/usr/lib/python2.6/site-packages/nailgun/orchestrator/stages.py", line 36, in stage_serialize
    tasks.extend(plugins.serialize())
  File "/usr/lib/python2.6/site-packages/nailgun/orchestrator/plugins_serializers.py", line 118, in serialize
    tasks.extend(self.create_repositories(plugins))
  File "/usr/lib/python2.6/site-packages/nailgun/orchestrator/plugins_serializers.py", line 132, in create_repositories
    if not uids or not plugin.repo_files(self.cluster):
  File "/usr/lib/python2.6/site-packages/nailgun/plugins/attr_plugin.py", line 194, in repo_files
    release_info = self.get_release_info(cluster.release)
  File "/usr/lib/python2.6/site-packages/nailgun/plugins/attr_plugin.py", line 191, in get_release_info
    return release_info[0]
IndexError: list index out of range

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/177164

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/177164
Committed: https://git.openstack.org/cgit/stackforge/fuel-web/commit/?id=5c363c91e2f3f3fe79a4547fcdb762d6cc6169b5
Submitter: Jenkins
Branch: master

commit 5c363c91e2f3f3fe79a4547fcdb762d6cc6169b5
Author: Evgeniy L <email address hidden>
Date: Fri Apr 24 13:47:03 2015 +0300

    Major version of plugin releases should be used

    Use special method which finds release by
    major version

    Change-Id: I50cc19ae57e2afa2e96bb7943cfc9193d282e50f
    Closes-bug: #1448060
    Closes-bug: #1440142

[Alexander Kurenyshev (akurenyshev)]

Verified on the #521 ISO.

Deploy failed with error "list index out of range" as expected.