$ git clone -n https://src.fedoraproject.org/rpms/gnome-boxes.git /var/lib/mock/f41-build-side-1-2793369-32695/root/chroot_tmpdir/scmroot/gnome-boxes
Cloning into '/var/lib/mock/f41-build-side-1-2793369-32695/root/chroot_tmpdir/scmroot/gnome-boxes'...
$ git fetch origin 5ebbda44d0f3fcb0a96467bb0e96252ed103ebb3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gnome-boxes
 * [new ref]         5ebbda44d0f3fcb0a96467bb0e96252ed103ebb3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5ebbda4 Update to 47.0