500 error code when running single action-execution with error

[Nikolay Makhotkin]

Steps to reproduce:

1. Use CLI to create action-execution:
  mistral run-action nova.servers_create '{"name": "nm-mistral", "flavor": "2", "image": "82065b4d-2c79-420d-adc3-310de275e922", "nics": [{"net-id": "wrong"}]}'

2. Get traceback

Traceback (most recent call last):

  File "/home/kolyan/projects/mistral/.tox/venv/local/lib/python2.7/site-packages/oslo_messaging/rpc/dispatcher.py", line 142, in _dispatch_and_reply
    executor_callback))

  File "/home/kolyan/projects/mistral/.tox/venv/local/lib/python2.7/site-packages/oslo_messaging/rpc/dispatcher.py", line 186, in _dispatch
    executor_callback)

  File "/home/kolyan/projects/mistral/.tox/venv/local/lib/python2.7/site-packages/oslo_messaging/rpc/dispatcher.py", line 129, in _do_dispatch
    result = func(ctxt, **new_args)

  File "/home/kolyan/projects/mistral/mistral/engine/rpc.py", line 122, in start_action
    **params

  File "/home/kolyan/projects/mistral/mistral/utils/__init__.py", line 107, in _logged
    return func(*args, **kw)

  File "/home/kolyan/projects/mistral/mistral/engine/default_engine.py", line 131, in start_action
    async=False

  File "/home/kolyan/projects/mistral/mistral/engine/action_handler.py", line 154, in run_action
    return _get_action_output(action_result)

  File "/home/kolyan/projects/mistral/mistral/engine/action_handler.py", line 167, in _get_action_output
    if result.is_success() else {'result': result.error})

AttributeError: 'unicode' object has no attribute 'is_success'

Need to fix on server-side.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/226742

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/226742
Committed: https://git.openstack.org/cgit/openstack/mistral/commit/?id=117dc15cf59a88d8ab6b193754e884a7a8218707
Submitter: Jenkins
Branch: master

commit 117dc15cf59a88d8ab6b193754e884a7a8218707
Author: Nikolay Mahotkin <email address hidden>
Date: Wed Sep 23 15:08:03 2015 +0300

    Fixing run action when error occurs

    Closes-Bug: #1498803

    Change-Id: I2e47ce5ce80c0d8918f4dc0d060935f321ccd9b9