[horde] Fatal Error: Horde isn't correctly configured for logging.

[jochem at mondrian-it.nl]

Running the current HEAD release of horde, I get the following error when
trying to go to http://domain.tld/horde/:

A fatal error has occurred
Horde is not correctly configured to log error messages. You must configure
at least a text file log in horde/config/conf.php.

These are my horde log settings in horde/config/conf.php:

$conf['log']['priority'] = PEAR_LOG_NOTICE;
$conf['log']['params'] = array();
$conf['log']['name'] = '/tmp/horde.log';
$conf['log']['params']['append'] = true;
$conf['log']['type'] = 'file';
$conf['log']['enabled'] = true;
$conf['log']['ident'] = 'HORDE';

Grepping for the error in /usr/share/php, I find it in one location,
Horde.php, which checks whether (some of ) the above variables are set. Even
though all the needed variables (as per the check in
/usr/share/php/Horde.php) seem to be set in conf.php, the error persists.

Using print_r to output the value of $conf['log'], gives the following
output:
Array 
( 
 [enabled] => 1
 [priority] => 7
)

It seems that somehow, some of the $conf['log'] values get removed from the
array.

Does anyone know what's causing this? I'm using PHP 4.4.0 on Apache 2 / SuSE
10.0.

Regards,

Jochem