Description of problem:
Using the heat API actions->check call will remove output values from existing heat stack.

Behavior observed with the CLI and Dashboard.

heat "Check Stack" button (Horizon)
&
"heat action-check <heat-stack>"

This will break stack updates and other operations depending on stack output values after this operation is executed.

Version-Release number of selected component (if applicable):
openstack-heat-engine-2015.1.2-4.el7ost.noarch
openstack-heat-common-2015.1.2-4.el7ost.noarch
openstack-heat-api-2015.1.2-4.el7ost.noarch


How reproducible:
100%

Steps to Reproduce:
1.  create a simple test heat stack that contains outputs

heat stack-create test -f test.yaml -e env.yaml
test.yaml[1]
env.yaml[2]

2. Verify stack create was successful and the output values.

$ heat stack-list
+--------------------------------------+------------+-----------------+----------------------+
| id                                   | stack_name | stack_status    | creation_time        |
+--------------------------------------+------------+-----------------+----------------------+
| 03bb28f6-5127-42b2-936d-a354416f7d99 | test       | CREATE_COMPLETE | 2016-01-17T22:25:13Z |
+--------------------------------------+------------+-----------------+----------------------+

$ heat output-list test
+------------+----------------------+
| output_key | description          |
+------------+----------------------+
| image_A    | No description given |
| ip_A       | IP address A server  |
+------------+----------------------+

$ heat output-show test ip_A
"172.16.40.9"

3. Run action-check on test stack and it completes successfully

$ heat action-check test
+--------------------------------------+------------+-------------------+----------------------+
| id                                   | stack_name | stack_status      | creation_time        |
+--------------------------------------+------------+-------------------+----------------------+
| 03bb28f6-5127-42b2-936d-a354416f7d99 | test       | CHECK_IN_PROGRESS | 2016-01-17T22:25:13Z |
+--------------------------------------+------------+-------------------+----------------------+

$ heat stack-list
+--------------------------------------+------------+----------------+----------------------+
| id                                   | stack_name | stack_status   | creation_time        |
+--------------------------------------+------------+----------------+----------------------+
| 03bb28f6-5127-42b2-936d-a354416f7d99 | test       | CHECK_COMPLETE | 2016-01-17T22:25:13Z |
+--------------------------------------+------------+----------------+----------------------+

4. Run heat output-show is now null

$ heat output-show test ip_A
null


Actual results:
heat stack output values become null 


Expected results:
The same output values should be returned after the action-check

Additional info:


[1] test.yaml
heat_template_version: 2013-05-23

description:

parameters:
  public_net_id:
    type: string
    description: ID of public network
    constraints:
      - custom_constraint: neutron.network
        description: Must be a valid network ID
  flavor:
    type: string
    description: Flavor to use
    constraints:
      - custom_constraint: nova.flavor
        description: Must be a valid flavor name
  image:
    type: string
    description: Name of image to use
    constraints:
      - custom_constraint: glance.image
        description: Must be a valid image name

resources:
  server:
    type: OS::Nova::Server
    properties:
      networks:
      - port:
          get_resource: server_port
      name: server_A
      image: { get_param: image }
      flavor: { get_param: flavor }
                  
  server_port:  
    type: OS::Neutron::Port
    properties:
      network_id: { get_param: public_net_id }

outputs:
  ip_A:
    description: IP address A server
    value: { get_attr: [ server, first_address ] }
  image_A:
    value: { get_param: image }


[2] env.yaml
parameters:
  flavor: m1.demo
  image: cirros
  public_net_id: b54b1eb9-8076-4b3a-92d3-1d5725b03fad