$ git clone -n https://src.fedoraproject.org/rpms/tuna.git /var/lib/mock/f45-build-37483-715/root/chroot_tmpdir/scmroot/tuna
Cloning into '/var/lib/mock/f45-build-37483-715/root/chroot_tmpdir/scmroot/tuna'...
$ git fetch origin 95c0305d970ce15e7a6cbeeea91dd9034e242d14:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/tuna
 * [new ref]         95c0305d970ce15e7a6cbeeea91dd9034e242d14 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 95c0305 Rebased to upstream tuna-0.21