$ git clone -n https://src.fedoraproject.org/rpms/gnome-shell.git /var/lib/mock/f41-build-842745-161701/root/chroot_tmpdir/scmroot/gnome-shell
Cloning into '/var/lib/mock/f41-build-842745-161701/root/chroot_tmpdir/scmroot/gnome-shell'...
$ git fetch origin b2403fff9cf260269dc62e4e4937abfc752f8775:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gnome-shell
 * [new ref]         b2403fff9cf260269dc62e4e4937abfc752f8775 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b2403ff Update to 47.beta