I wrote:

I don't have a lot of time to poke at this today, but I'll
make another test run on an s390x build host without that
patch, but where I can save the output and post it
somewhere.

For the Fedora packaging, it will be something like this:

    make -C t all || {
        (cd t && ./t5620-backfill.sh -ix);
        ./print-failed-test-output;
    }

The matches file is empty.

    $ ls -lhn batch-trace matches 
    -rw-r--r--. 1 1000 1000 31K Mar 28 11:09 batch-trace
    -rw-r--r--. 1 1000 1000   0 Mar 28 11:09 matches

The only match in batch-trace for promisor fetch_count is
from the previous test:

    $ grep -e '"category":"promisor","key":"fetch_count","value":' batch-trace
    {"event":"data","sid":"20250328T150939.623820Z-H9aa15b67-P0008f613","thread":"main","time":"2025-03-28T15:09:39.625484Z","file":"promisor-remote.c","line":55,"repo":1,"t_abs":0.001777,"t_rel":0.001777,"nesting":1,"category":"promisor","key":"fetch_count","value":"48"}

The trash directory for the test run is here, in case anyone
wants to poke at it:

    https://tmz.fedorapeople.org/t5620-backfill-trash-dir.tar.gz

The full build log is available as well:

    https://tmz.fedorapeople.org/git-2.49.0-s390x-build.log

If you search for 'BEGIN BASE64 MESSAGE' in that, it
provides a command which can be used to extract the full
test-results directory.  That's used to get the output from
the build hosts where shell access isn't available.  I don't
know that it's got anything which isn't in the trash
directory tarball which I already extracted, but it's there
just in case.

-- 
Todd