$ git clone -n https://src.fedoraproject.org/rpms/libblockdev.git /var/lib/mock/f41-build-847931-164250/root/chroot_tmpdir/scmroot/libblockdev
Cloning into '/var/lib/mock/f41-build-847931-164250/root/chroot_tmpdir/scmroot/libblockdev'...
$ git fetch origin b3ec42b3b2457f93760eed9562c7afeb73988fd5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libblockdev
 * [new ref]         b3ec42b3b2457f93760eed9562c7afeb73988fd5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b3ec42b New version 3.2.0