$ git clone -n https://src.fedoraproject.org/rpms/libXext.git /var/lib/mock/f45-build-15763-479/root/chroot_tmpdir/scmroot/libXext
Cloning into '/var/lib/mock/f45-build-15763-479/root/chroot_tmpdir/scmroot/libXext'...
$ git fetch origin ef20ef23327573efdd7e77cb43e671d8a23ee40e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libXext
 * [new ref]         ef20ef23327573efdd7e77cb43e671d8a23ee40e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ef20ef2 Remove stale 'xmlto' BuildRequires