[Dev-luatex] Braced file names for openout

Hello, \openin and \input accept file names in braces (well, as <general text>) while \openout does not: luatex '\immediate \openout 12 = {abc} \end' makes a file named "{abc}.tex" and not "abc". I'm using LuaTeX, Version beta-0.79.1 (TeX Live 2014) (rev 4971). Is this by design or a bug ? Best regards, Bruno