Merged to master

Yes, it is also just a warning, although I still think it's a warning 
that can be avoided as it might lead to conufsion on production 
servers seeing something like that:

2012-08-31T19:17:33+02:00 WARN: HORDE [horde] PHP ERROR: is_dir() [<a 
href='function.is-dir'>function.is-dir</a>]: open_basedir restriction 
in effect. File(/tmp/sync) is not within the allowed path(s): 
(/var/www/vhosts/horde.example.com/www/:/var/www/vhosts/horde.example.com/pear:/var/www/upload_tmp_dir/horde.example.com/:/var/www/session.save_path/horde.example.com/:/var/www/vhosts/horde.example.com/logs/:/var/www/vhosts/horde.example.com/tmp/:/etc/resolv.conf:/.pearrc) [pid 13430 on line 281 of 
"/var/www/vhosts/horde.example.com/pear/php/Horde/SyncMl/Backend.php"]

Relevant settings were:

$conf['activesync']['logging']['type'] = 'horde';

and global options were like:

$conf['log']['priority'] = 'INFO';
$conf['log']['ident'] = 'HORDE';

Not necessary, this is only for debugging purposes.

In the syncml code you can find usage of a fixed location to write 
things to (/tmp/sync), this directory might not be accessible due to 
open base dir restrictions -> we should use horde's builtin tmp 
function.

Pull request: https://github.com/horde/horde/pull/17