$ git clone -n https://src.fedoraproject.org/rpms/signon.git /var/lib/mock/f40-build-2109817-50642/root/chroot_tmpdir/scmroot/signon
Cloning into '/var/lib/mock/f40-build-2109817-50642/root/chroot_tmpdir/scmroot/signon'...
$ git fetch origin dc17de118fdf3cf523891978cefc4d57744335ea:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/signon
 * [new ref]         dc17de118fdf3cf523891978cefc4d57744335ea -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at dc17de1 Rebuild