$ git clone -n https://src.fedoraproject.org/rpms/sonic-visualiser.git /var/lib/mock/f40-build-2177195-51096/root/chroot_tmpdir/scmroot/sonic-visualiser
Cloning into '/var/lib/mock/f40-build-2177195-51096/root/chroot_tmpdir/scmroot/sonic-visualiser'...
$ git fetch origin b4207ad50327d34de220d59f513872b4b481e998:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/sonic-visualiser
 * [new ref]         b4207ad50327d34de220d59f513872b4b481e998 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b4207ad Rebuild for capnproto 1.0.1