Apache 2.4, mod_geoip GeoIPScanProxyHeaders “On” não funciona

Question

apache httpd.conf

LoadModule geoip_module modules/mod_geoip.so
<IfModule mod_geoip.c>
    GeoIPEnable On
    GeoIPEnableUTF8 On
    GeoIPOutput Env
    GeoIPScanProxyHeaders On
    GeoIPDBFile /usr/share/GeoIP/GeoIP.dat IndexCache
</IfModule>

Solicitação HTTP:

GET /test.php HTTP/1.1
Host: XXXXXXXXXXXXXXXXXXXXXXXX
Connection: keep-alive
X-Forwarded-For: 150.XX.XX.XXX

página de teste /test.php

<?php

if( isset($_SERVER['GEOIP_COUNTRY_CODE']) ){
    echo 'GEOIP_COUNTRY_CODE: '.$_SERVER['GEOIP_COUNTRY_CODE'].'<br>';
}

if( isset($_SERVER['GEOIP_COUNTRY_NAME']) ){
    echo 'GEOIP_COUNTRY_NAME: '.$_SERVER['GEOIP_COUNTRY_NAME'].'<br>';
}

if( isset($_SERVER['GEOIP_ADDR']) ){
    echo 'GEOIP_ADDR: '.$_SERVER['GEOIP_ADDR'].'<br>';
}

if( isset($_SERVER['HTTP_X_FORWARDED_FOR']) ){
    echo 'HTTP_X_FORWARDED_FOR: '.$_SERVER['HTTP_X_FORWARDED_FOR'].'<br>';
}

echo 'REMOTE_ADDR: '.$_SERVER['REMOTE_ADDR'].'<br>';

Saída

GEOIP_COUNTRY_CODE: IT
GEOIP_COUNTRY_NAME: Italy
GEOIP_ADDR: 66.XX.XX.XXX
HTTP_X_FORWARDED_FOR: 150.XX.XX.XXX
REMOTE_ADDR: 66.XX.XX.XXX

esperado

GEOIP_COUNTRY_CODE: US
GEOIP_COUNTRY_NAME: United States
GEOIP_ADDR: 150.XX.XX.XXX
HTTP_X_FORWARDED_FOR: 150.XX.XX.XXX
REMOTE_ADDR: 66.XX.XX.XXX

mod_geoip parece não usar ipaddress HTTP_X_FORWARDED_FOR ... por quê?

Server version: Apache/2.4.18 (Unix) Server built:   Feb  4 2016 17:41:16
Loaded Modules:
 core_module (static)
 so_module (static)
 http_module (static)
 authn_file_module (shared)
 authn_core_module (shared)
 authz_host_module (shared)
 authz_groupfile_module (shared)
 authz_user_module (shared)
 authz_core_module (shared)
 access_compat_module (shared)
 auth_basic_module (shared)
 socache_shmcb_module (shared)
 reqtimeout_module (shared)
 filter_module (shared)
 substitute_module (shared)
 deflate_module (shared)
 mime_module (shared)
 log_config_module (shared)
 env_module (shared)
 expires_module (shared)
 headers_module (shared)
 setenvif_module (shared)
 version_module (shared)
 proxy_module (shared)
 proxy_connect_module (shared)
 proxy_ftp_module (shared)
 proxy_http_module (shared)
 proxy_fcgi_module (shared)
 proxy_scgi_module (shared)
 proxy_wstunnel_module (shared)
 proxy_ajp_module (shared)
 proxy_balancer_module (shared)
 proxy_express_module (shared)
 slotmem_shm_module (shared)
 lbmethod_byrequests_module (shared)
 lbmethod_bytraffic_module (shared)
 lbmethod_bybusyness_module (shared)
 lbmethod_heartbeat_module (shared)
 mpm_event_module (shared)
 unixd_module (shared)
 status_module (shared)
 autoindex_module (shared)
 negotiation_module (shared)
 dir_module (shared)
 actions_module (shared)
 alias_module (shared)
 rewrite_module (shared)
 geoip_module (shared)

Eu suspeito que a versão do meu geoip é antiga

$ dpkg -l | grep apache

talvez seja

ii  libapache2-mod-geoip   1.2.8-2  amd64        
    GeoIP support for apache2