$ git clone -n https://src.fedoraproject.org/rpms/appstream.git /var/lib/mock/f42-build-3343244-44993/root/chroot_tmpdir/scmroot/appstream
Cloning into '/var/lib/mock/f42-build-3343244-44993/root/chroot_tmpdir/scmroot/appstream'...
$ git fetch origin 9067fb39be34805f9120a05a9e0230ab0e3a3a70:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/appstream
 * [new ref]         9067fb39be34805f9120a05a9e0230ab0e3a3a70 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9067fb3 Update to 1.0.4