Description of problem:

When I update a test case, some of test runs get updated accordingly without 'update' operation under certain circumstance.

This is a critical issue in terms of keeping the past test run record or history (combination of mark and test case) for future use. Past test run was ran against test case revision but if its test cases get updated, the results are not meaningful at all.

Version-Release number of selected component (if applicable):
Nitrate 3.3-4 

How reproducible:
always

Steps to Reproduce:
1. Create a test run
2. Execute a test run
3. Update test case in the test plan
  
Actual results:
Test case gets updated without 'update' operation and overwrite past testing record.

Expected results:
As far as I think updating or not each test run can be handled by users.

Additional info: