$ git clone -n https://src.fedoraproject.org/rpms/root.git /var/lib/mock/f40-build-2661628-66921/root/chroot_tmpdir/scmroot/root
Cloning into '/var/lib/mock/f40-build-2661628-66921/root/chroot_tmpdir/scmroot/root'...
$ git fetch origin 29328ac08b05e64a4200cb920cf0ffb3d681b5a9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/root
 * [new ref]         29328ac08b05e64a4200cb920cf0ffb3d681b5a9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 29328ac Support StandardSymbolsPS.otf