$ git clone -n https://src.fedoraproject.org/rpms/libnbd.git /var/lib/mock/f40-build-2702306-70612/root/chroot_tmpdir/scmroot/libnbd
Cloning into '/var/lib/mock/f40-build-2702306-70612/root/chroot_tmpdir/scmroot/libnbd'...
$ git fetch origin 26205aa4aa65c97c6e3fd23a2100dad4d46d1b45:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libnbd
 * [new ref]         26205aa4aa65c97c6e3fd23a2100dad4d46d1b45 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 26205aa New stable branch version 1.20.0