Repeated schema mismatch wrt celery_taskmeta

[Jonathan Lange]

On our staging system we are frequently seeing errors like this::

[2012-08-20 09:40:09,184: CRITICAL/MainProcess] Task djpkgme.tasks.BuildPackageTask[48a06c25-d894-49e3-ad07-88fe3f7e5b9c] INTERNAL ERROR: DatabaseError('column celery_taskmeta.hidden does not exist\nLINE 1: ...meta"."date_done", "celery_taskmeta"."traceback", "celery_ta...\n ^\n',)
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/celery/execute/trace.py", line 178, in trace_task
    store_result(uuid, retval, SUCCESS)
...
  File "/usr/lib/python2.7/dist-packages/django/db/backends/postgresql_psycopg2/base.py", line 44, in execute
    return self.cursor.execute(query, args)
DatabaseError: column celery_taskmeta.hidden does not exist
LINE 1: ...meta"."date_done", "celery_taskmeta"."traceback", "celery_ta... ^

The error appears to be legitimate::

staging_myapps_library=# \d celery_taskmeta
                                   Table "public.celery_taskmeta"
  Column | Type | Modifiers
-----------+--------------------------+--------------------------------------------------------------
 id | integer | not null default nextval('celery_taskmeta_id_seq'::regclass)
 task_id | character varying(255) | not null
 status | character varying(50) | not null default 'PENDING'::character varying
 result | text |
 date_done | timestamp with time zone | not null
 traceback | text |
Indexes:
    "celery_taskmeta_pkey" PRIMARY KEY, btree (id)
    "celery_taskmeta_task_id_key" UNIQUE CONSTRAINT, btree (task_id)