$ git clone -n https://src.fedoraproject.org/rpms/python-b4.git /var/lib/mock/f40-build-2633967-65970/root/chroot_tmpdir/scmroot/python-b4
Cloning into '/var/lib/mock/f40-build-2633967-65970/root/chroot_tmpdir/scmroot/python-b4'...
$ git fetch origin b47fa02b46cf81da1c3ee00ec784760f35dd46b8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/python-b4
 * [new ref]         b47fa02b46cf81da1c3ee00ec784760f35dd46b8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b47fa02 Update to 0.13.0 (rhbz#2245336)