$ git clone -n https://src.fedoraproject.org/rpms/mesa-demos.git /var/lib/mock/f41-build-750974-13388/root/chroot_tmpdir/scmroot/mesa-demos
Cloning into '/var/lib/mock/f41-build-750974-13388/root/chroot_tmpdir/scmroot/mesa-demos'...
$ git fetch origin 4be1f64607ebd7859ca5334c482e32d902f7022d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mesa-demos
 * [new ref]         4be1f64607ebd7859ca5334c482e32d902f7022d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4be1f64 Eliminate use of obsolete %patchN syntax (#2283636)