Description of problem:
Go to 'TESTING'->'Search Runs' page. Input something not existed in 'Case Run Assignee' field, click 'Search' button, although there is no run in result list, 'No test runs found' is not shown.

If not use 'Case Run Assignee' field for the search, there will be a 'No test runs found' if no result.

Version-Release number of selected component (if applicable):
3.8.5

How reproducible:
100%

Steps to Reproduce:
1.Go to 'TESTING'->'Search Runs' page.
2. Input something not existed in 'Case Run Assignee' field, click 'Search' button.

Actual results:
2.Although there is no run in result list, 'No test runs found' is not shown.

Expected results:
2.'No test runs found' is shown.