Installing emoncms - redis problem on openSUSE system

Again, I prefer to run the stable distro versions of things to avoid random breakages.

I just wrote a little PHP script:

<?php

if (class_exists('Redis')) {
    echo "redis is there";
}               
else {
    echo "no redis";
}               

and it says:

$ php ./test_redis.php
redis is there

so I don’t understand why process_settings.php is failing to find the class?