See https://copr.fedorainfracloud.org/coprs/g/python/python3.8/package/python-tinyrpc/ for actual logs. This report is automated and not very verbose, but feel free to ping me for help.
The actual issue is related to pytest update to > 4 while it's pinned in upstream to 3.6.3. Apparently pytest 4 has broken backwards compatibility. I'v reported it in https://github.com/mbr/tinyrpc/issues/75 and i will disable the unit tests to get package builds fine.
I've pushed https://src.fedoraproject.org/rpms/python-tinyrpc/c/ee92a4c0923e5fc8db9735b409134326c0800a2a?branch=master which should fix it. Could you try to rebuild python-tinyrpc-1.0.1-1.fc31 with python-3.8?
It works, thanks.