On Sun, Feb 07, 2016 at 08:44:50PM +0100, Lars Schneider wrote:

quoted

Are there any other reasons why current_config_filename() would return
NULL, besides command-line config? I don't think so. It looks like we
can read config from stdin, but we use the token "<stdin>" there for the
name field (another ambiguity!).

During my testing I haven't found any other case either. To be honest
I didn't know the "stdin" way to set the config! I added a test case for 
that, too!

I didn't remember it either, until I peeked at the code trying to answer my
own question. Ironically, I appear to have been involved in reviewing
the patches that added it. :-/

-Peff