pkgset: Compare future events correctly
    
    It is possible to try to re-run a compose with old event. When trying to
    reuse pkgset data, we must use set the bounds not based on
    current/reused event, but actually check which was first.
    
    JIRA: CWFHEALTH-495
    Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>