$ git clone -n https://src.fedoraproject.org/rpms/gnome-nibbles.git /var/lib/mock/f39-build-2033377-47748/root/chroot_tmpdir/scmroot/gnome-nibbles
Cloning into '/var/lib/mock/f39-build-2033377-47748/root/chroot_tmpdir/scmroot/gnome-nibbles'...
$ git fetch origin 7749761c5bcf1e06827ac225504c9a62344e5aed:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gnome-nibbles
 * [new ref]         7749761c5bcf1e06827ac225504c9a62344e5aed -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7749761 Update to 4.0.0