I installed drupal-4.6.5, enabled localization support and tried to import the german .so file using the option provided. I received following errors:

warning: fopen(): open_basedir restriction in effect. File(/tmp/phpsumRe6) is not within the allowed path(s): (/home/user) in /home/user/public_html/drupal-4.6.5/includes/locale.inc on line 273.
warning: fopen(/tmp/phpsumRe6): failed to open stream: Operation not permitted in /home/user/public_html/drupal-4.6.5/includes/locale.inc on line 273.
warning: Cannot modify header information - headers already sent by (output started at /home/user/public_html/drupal-4.6.5/includes/common.inc:384) in /home/user/public_html/drupal-4.6.5/includes/common.inc on line 192.

Of course the import failed.

Why does Drupal try to access /tmp and how can I changed it?
Searching "/tmp" I found file.inc containing following line:
define('FILE_DIRECTORY_TEMP', IS_WINDOWS ? 'c:\\windows\\temp' : '/tmp');

I was not absolutely sure what this does, but I tried to change '/tmp' (which is not my upload_tmp_dir) to '/home/user/phptemp' (which is), but this did not help. I didn't expect it anyway, because if this constant was to contain the upload_tmp_dir something like

if(!empty(get_cfg_var('upload_tmp_dir')) define('FILE_DIRECTORY_TEMP',get_cfg_var('upload_tmp_dir'));
else die('UPLOAD_TMP_DIR not specified! Please specify manually in '.$PHP_SELF.'.');

would have been better.

Of course I have provided proper settings on the "administer -> settings" page.

Anyone out there who could help me with this issue?