/public Folder as Document Root + Clean URL

AC is configured with /public as document root. Now I'm tweaking it to serve clean URL. I have done:

1) .htaccess in the public directory (btw, +FollowSymlinks should be added to the online document)

Options -Indexes +FollowSymLinks
<IfModule mod_rewrite.c>
  RewriteEngine On

  RewriteCond %{REQUEST_FILENAME} -f [OR]
  RewriteCond %{REQUEST_FILENAME} -d
  RewriteRule ^(.+) - [PT,L]

  RewriteRule ^projects_icons/(.*)$ projects_icons/$1 [L]
  RewriteRule ^avatars/(.*)$ avatars/$1 [L]
  RewriteRule ^logos/(.*)$ logos/$1 [L]
  RewriteRule ^thumb.php$ thumb.php [L]
  RewriteRule ^captcha.php$ captcha.php [L]
  RewriteRule ^$ index.php [L]
  RewriteRule ^(.*) index.php?path_info=$1 [L]
</IfModule>

2) made necessary changes to config/config.php

define('ROOT_URL', 'http://ac.domain.com');
define('URL_BASE', ROOT_URL . '/');
define('ASSETS_URL', ROOT_URL . '/assets');
//define('PATH_INFO_THROUGH_QUERY_STRING', true);

Everything seems ok, at least I can log in. So far there is one problem, the brand/logo.gif is broken. It is being referenced as http://ac.domain.com/public/brand/logo.gif. Seems to be a problem with function.brand.php.

I want to avoid changing function.brand.php directly. What's the proper fix for this?

Yes, I did everything by the book. I did the "/public Folder as Document Root" first and it worked fine. Then I did the clean URL configuration change. Now the brand/logo.gif is not referenced correctly.

Actually, if you like at function.brand.php, you can easily spot the error:

case 'logo':
  return URL_BASE == ROOT_URL . '/' ? ROOT_URL . '/public/brand/logo.gif' : ROOT_URL . '/brand/logo.gif';

As you can see, if URL_BASE == ROOT_URL . '/', then ROOT_URL . '/public/brand/logo.gif' is returned. Which is wrong.