$ git clone -n https://src.fedoraproject.org/rpms/golang-github-ghemawat-stream.git /var/lib/mock/f39-build-1513078-35586/root/chroot_tmpdir/scmroot/golang-github-ghemawat-stream
Cloning into '/var/lib/mock/f39-build-1513078-35586/root/chroot_tmpdir/scmroot/golang-github-ghemawat-stream'...
$ git fetch origin 22831404dba40856fba91e1f183d4c9376a74079:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-github-ghemawat-stream
 * [new ref]         22831404dba40856fba91e1f183d4c9376a74079 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2283140 Fix FTBFS