no move (rename) operation for "Shared" directory

lib/files.php

@@ -170,7 +170,7 @@ class OC_Files {
 	* @param file $target
 	*/
 	public static function move($sourceDir,$source,$targetDir,$target){
-		if(OC_User::isLoggedIn()){
+		if(OC_User::isLoggedIn() && ($sourceDir != '' || $source != 'Shared')){
 			$targetFile=self::normalizePath($targetDir.'/'.$target);
 			$sourceFile=self::normalizePath($sourceDir.'/'.$source);
 			return OC_Filesystem::rename($sourceFile,$targetFile);