[Update] status bar do not show progress after update/rollback

[Tatyanka]

Steps to Reproduce:
1. Run upgrade
2. Run update from current release to current
3. reset cluster
4. Add 2 nodes
5. Deploy changes

Expected Result:
Progress bar show current progress of deployment task

Actual Result:
Progress bar stay on 0 value with traces in rpc consumer:
[7f2284093700] (receiverd) Traceback (most recent call last):
  File "/usr/lib/python2.6/site-packages/nailgun/rpc/receiverd.py", line 47, in consume_msg
    callback(**body["args"])
  File "/usr/lib/python2.6/site-packages/nailgun/rpc/receiver.py", line 293, in provision_resp
    objects.Task.update(task, data)
  File "/usr/lib/python2.6/site-packages/nailgun/objects/task.py", line 250, in update
    super(Task, cls).update(instance, data)
  File "/usr/lib/python2.6/site-packages/nailgun/objects/base.py", line 121, in update
    db().flush()
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/session.py", line 1718, in flush
    self._flush(objects)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/session.py", line 1789, in _flush
    flush_context.execute()
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/unitofwork.py", line 331, in execute
    rec.execute(self)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/unitofwork.py", line 475, in execute
    uow
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/persistence.py", line 59, in save_obj
    mapper, table, update)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/orm/persistence.py", line 485, in _emit_update_statements
    execute(statement, params)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/engine/base.py", line 1449, in execute
    params)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/engine/base.py", line 1584, in _execute_clauseelement
    compiled_sql, distilled_params
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/engine/base.py", line 1698, in _execute_context
    context)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/engine/base.py", line 1691, in _execute_context
    context)
  File "/usr/lib64/python2.6/site-packages/sqlalchemy/engine/default.py", line 331, in do_execute
    cursor.execute(statement, parameters)
IntegrityError: (IntegrityError) null value in column "status" violates not-null constraint
DETAIL: Failing row contains (20, 1, c90673c5-b08f-45a5-8cc1-46a6e83bb3e4, provision, null, null, 7, {"args": {"task_uuid": "c90673c5-b08f-45a5-8cc1-46a6e83bb3e4", "..., {}, 17, 0.4).
 'UPDATE tasks SET status=%(status)s, progress=%(progress)s WHERE tasks.id = %(tasks_id)s' {'status': None, 'progress': 7, 'tasks_id': 20}

[Evgeniy L (rustyrobot)]

It had to be fixed here https://bugs.launchpad.net/fuel/+bug/1335170
And it affects only 5.1 release.