$ git clone -n https://src.fedoraproject.org/rpms/tar.git /var/lib/mock/f44-build-18-5/root/chroot_tmpdir/scmroot/tar
Cloning into '/var/lib/mock/f44-build-18-5/root/chroot_tmpdir/scmroot/tar'...
$ git fetch origin 9b8709a75091d2fa82d667a4f37d37e9b9b1c74c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/tar
 * [new ref]         9b8709a75091d2fa82d667a4f37d37e9b9b1c74c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9b8709a Update %changelog