osbs-client fails to build because the source archive isn't listed. Please make sure to use `fedpkg new-sources` to record new source archives in the `sources` file, and to upload them to the look-aside cache.
I can download the sources now. Running anew build in https://copr.fedorainfracloud.org/coprs/g/python/python3.8/
+ cd osbs-client-b2a5fac97fa9880b23ac835d01dd99e29d2938a5 /var/tmp/rpm-tmp.2H8LLw: line 38: cd: osbs-client-b2a5fac97fa9880b23ac835d01dd99e29d2938a5: No such file or directory error: Bad exit status from /var/tmp/rpm-tmp.2H8LLw (%prep)
I've uploaded new sources. It fixed the problem.