CiviCRM misses to recognize drupal's sites.php

If you have a Multi Site installation with Drupal and you are using sites.php in the sites folder to determine which domain belongs to which folder, you can't install CiviCRM because it seems not to recognize sites.php.

Example: You have test.example.com and test2.example.com, in the sites folder you have two folders named 1 and 2. In sites.php you have two lines for these two domains:
$sites[' test.example.com'] = '1';
$sites['test2.example.com'] = '2';

But the CiviCRM install script searches in sites/default for civicrm.settings.php file and if found it breaks up with an error message.