[ESS] ess-history-file nil is not respected anymore

[Marius Hofert]

Hi,

I have

(setq ess-history-file nil)

in ~/.emacs to avoid that .Rhistory files are written. This worked well
for me for quite some time until I updated to 13.05-1 [rev. 5586
(2013-05-17)]. Since then it shows .Rhistory and not nil (maybe this is
due to
https://github.com/emacs-ess/ESS/commit/710f4e462f0ede6e9f09ae9bd46f83ebaa3cfb77
?).

The question is, how can I get 'nil', so really no .Rhistory being
written?

Thanks & cheers,

Marius