$ git clone -n https://src.fedoraproject.org/rpms/gnome-shell.git /var/lib/mock/f40-build-773742-127364/root/chroot_tmpdir/scmroot/gnome-shell
Cloning into '/var/lib/mock/f40-build-773742-127364/root/chroot_tmpdir/scmroot/gnome-shell'...
$ git fetch origin 8cfa0c06f5a5abf65f3af82c3808220cac89aefe:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gnome-shell
 * [new ref]         8cfa0c06f5a5abf65f3af82c3808220cac89aefe -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8cfa0c0 Exclude i686