bug#31902: 27.0.50; new buffer /dev/null

[Eli Zaretskii]

> From: markusffm@fn.de
> Date: Tue, 19 Jun 2018 17:22:06 +0200
> 
> 
> recently a formerly unknown buffer names '/dev/null' opens while opening
> any elisp code file, with the contents
> Process elisp-flymake-byte-compile stderr finished.
> This never happened before. How to get rid of it?

João, can you please look into this issue?

Thanks.