Compare (resolution set): https://bugs.gentoo.org/buglist.cgi?list_id=89803&short_desc=rxvt-unicode&resolution=---&resolution=FIXED&resolution=INVALID&resolution=WONTFIX&resolution=LATER&resolution=REMIND&resolution=DUPLICATE&resolution=WORKSFORME&resolution=CANTFIX&resolution=NEEDINFO&resolution=TEST-REQUEST&resolution=UPSTREAM&resolution=OBSOLETE&query_format=advanced&bug_status=RESOLVED&bug_status=VERIFIED&bug_status=CLOSED&short_desc_type=allwordssubstr with (resolution set to "---"): https://bugs.gentoo.org/buglist.cgi?list_id=89799&short_desc=rxvt-unicode&resolution=---&query_format=advanced&bug_status=RESOLVED&bug_status=VERIFIED&bug_status=CLOSED&short_desc_type=allwordssubstr
I must add that Resolution : "---" is set by default. Unsetting it manually in the search form fixes the issue.
Maybe we could make it automatically deselect resolution when status is selected (and resolution wasn't changed).