Option to log just to stderr
We want the default log to stderr (systemd journal in our case), but we don't want an additional log file.
Right now we use this workaround (d84741a):
It works as intended, but produces this confusing error message in case of a crash:
(EE) Please also check the log file at "/dev/null" for additional information.
Related issue: https://github.com/NixOS/nixpkgs/issues/44348
host os: Linux 4.14.59, NixOS 18.03.133004.a1299c9951b (Impala)