Index: class-wp-filesystem-base.php
===================================================================
--- class-wp-filesystem-base.php	(revision 17525)
+++ class-wp-filesystem-base.php	(working copy)
@@ -152,7 +152,7 @@
 		if ( isset($this->cache[ $folder ] ) )
 			return $this->cache[ $folder ];
 
-		if ( $this->exists($folder) ) { //Folder exists at that absolute path.
+		if ( $this->is_dir($folder) ) { //Folder exists at that absolute path.
 			$folder = trailingslashit($folder);
 			$this->cache[ $folder ] = $folder;
 			return $folder;