$ git clone -n https://src.fedoraproject.org/rpms/gnome-nibbles.git /var/lib/mock/f42-build-side-1-3506370-45996/root/chroot_tmpdir/scmroot/gnome-nibbles
Cloning into '/var/lib/mock/f42-build-side-1-3506370-45996/root/chroot_tmpdir/scmroot/gnome-nibbles'...
$ git fetch origin 9f5fc4aa81101b8c03936c28e9eaa30e3e544c86:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gnome-nibbles
 * [new ref]         9f5fc4aa81101b8c03936c28e9eaa30e3e544c86 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9f5fc4a Update to 4.2.2