$ git clone -n https://src.fedoraproject.org/rpms/gnome-nibbles.git /var/lib/mock/f43-build-58980615-6569641/root/chroot_tmpdir/scmroot/gnome-nibbles
Cloning into '/var/lib/mock/f43-build-58980615-6569641/root/chroot_tmpdir/scmroot/gnome-nibbles'...
$ git fetch origin c9a8ffcf0414c0931da75df57d11c39d59394d38:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gnome-nibbles
 * [new ref]         c9a8ffcf0414c0931da75df57d11c39d59394d38 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c9a8ffc Update to 4.2.2