The feature introduced with bug 10937 appears to be broken on current master. You can add a search category and the display on the advanced search page is correct, but the search won't return any results.
I don't think it's more broken than when it has been pushed. If you select a term, you will get results. I only get no result when I select the item type group as unique filter. It's caused by: 110 elsif ((@params>=1) || ($cgi->param("q")) || ($cgi->param('multibranchlimit')) || ($cgi->param('limit-yr')) ) { 111 $template_name = 'opac-results.tt'; 112 } Which won't set the result page if searchcat (only) is passed.
*** This bug has been marked as a duplicate of bug 20722 ***