6a7ac8d blocker_list: don't display update popup needlessly

Authored and Committed by kparal a year ago
    blocker_list: don't display update popup needlessly
    
    The update popup was quite annoying, because it displayed over every row, even
    when there was no update present for that bug. With this change, the popup only
    shows on rows where there is some update available.
    
    Merges: https://pagure.io/fedora-qa/blockerbugs/pull-request/181