Adjust packbuilder tests across the board
    
    There are more things than different compression libraries which made
    these tests non-deterministic. Apply an upstream patch which makes them
    not expect packfiles to have certain verbatim contents across the board
    because this also broke with libgit2_1.7 on EPEL8/s390x.
    
    [skip changelog]
    
    Signed-off-by: Nils Philippsen <nils@redhat.com>