Index: wp-admin/includes/file.php
===================================================================
--- wp-admin/includes/file.php	(revision 23084)
+++ wp-admin/includes/file.php	(working copy)
@@ -79,6 +79,9 @@
  * @return string Full filesystem path to the root of the WordPress installation
  */
 function get_home_path() {
+	if ( defined( 'HOMEPATH' ) )
+		return HOMEPATH;
+
 	$home = get_option( 'home' );
 	$siteurl = get_option( 'siteurl' );
 	if ( ! empty( $home ) && 0 !== strcasecmp( $home, $siteurl ) ) {