CiviCRM installer for Drupal assumes CiviCRM is being installed on the default site

The installer wizard for CiviCRM assumes that the installation is occurring on the default site.

For a multi-site install, Drupal modules should default to using sites/site.domain.name/files and sites/site.domain.name/civicrm.settings.php

However, the CiviCRM installer requires that the folders files (in drupal root) and sites/default are writeable. It will not proceed until these conditions are met.

If these conditions are met, once the installation is complete, CiviCRM gives an error about not being able to read sites/site.domain.name/civicrm.settings.php (the config has been written to sites/default/civicrm.settings.php instead).

I believe the folder "files" is no longer required on Drupal multisite installs, and is deprecated in favour of default/files or site.domain.name/files