$ git clone -n https://src.fedoraproject.org/rpms/cpu-x.git /var/lib/mock/f39-build-1587296-38221/root/chroot_tmpdir/scmroot/cpu-x
Cloning into '/var/lib/mock/f39-build-1587296-38221/root/chroot_tmpdir/scmroot/cpu-x'...
$ git fetch origin eabc78ab6a1bbe8755f6d9e0fe78d506c67f3133:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/cpu-x
 * [new ref]         eabc78ab6a1bbe8755f6d9e0fe78d506c67f3133 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at eabc78a build: Ported to C++ so gtkmm-3.0 used now