Description of problem:

Under System Set Manager, Errata category filtering not working.

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

Tested on Satellite 5.7.0

How reproducible:

every time.

Steps to Reproduce:
1. Login to Satellite as admin. 
2. click on 'Systems'.
3. select a any system with Errata.
4. click 'Manage' in the right corner above to go into System Set Manager view.
5. click on the 'Errata' tab.
6. open the dropdown box and select any category to be filtered, then click on "Show".

Actual results:

The returned list shows ALL the erratas. The dropdown box will go back to 'All', as if step 6 doesn't have any effect.

Expected results:

The returned list is from the chosen category in step 6.