Description of problem:
as the subject

Version-Release number of selected component (if applicable):
v3.8.9-1 on test server

How reproducible:
100%

Steps to Reproduce:
1.invoke the method as:n.TestPlan.update(14139,{'Product__product_version':388})
2.invoke the method as:n.TestRun.update(141243,{'Product__product_version':388})
Then check the UI pages or invoke n.TestPlan.get(14139) and n.TestRun.get(141243) to get the results.

Actual result:
In [6]: n.TestPlan.update(14139,{'Product__product_version':388})
Out[6]: 
[{'attachment': [],
  'author': 'tzhao',
  'author_id': 4701,
  'case': [],
  'component': [54321],
  'create_date': '2014-05-26 11:45:18',
  'env_group': [3],
  'extra_link': None,
  'is_active': True,
  'name': 'Test Plan RHEL',
  'owner': None,
  'owner_id': None,
  'parent': 'Barrier Translator',
  'parent_id': 14136,
  'plan_id': 14139,
  'product': 'RHEL Tests',
  'product_id': 182,
  'product_version': 'RHEL6',
  'product_version_id': 389, 
  'tag': [6782],
  'type': 'Integration',
  'type_id': 2}]

In [7]: n.TestRun.update(141243,{'Product__product_version':388})
Out[7]: 
[{'auto_update_run_status': False,
  'build': 'RHSA-2.0-20140613.n.0',
  'build_id': 4876,
  'cc': [],
  'default_tester': 'tzhao',
  'default_tester_id': 4701,
  'env_value': [],
  'environment_id': 0,
  'errata_id': 1132,
  'estimated_time': '00:00:00',
  'manager': 'tzhao',
  'manager_id': 4701,
  'notes': 'test',
  'plan': 'Spacewalk to Satellite Transitioning',
  'plan_id': 389,
  'plan_text_version': 2,
  'product_version': 1623,      
  'run_id': 141243,
  'start_date': '2014-05-26 11:45:52',
  'stop_date': None,
  'summary': 'Test Run',
  'tag': []}]

Expected results:
both the plan and run product version should be updated to be the new values.

Additional info: