[ESS] Prevent ESS From Writing .Rhistory

[Lionel Henry]

> On 9 sept. 2016, at 12:00, Stephen Eglen <sje30 using cam.ac.uk> wrote:
>> For these users,
>> it seems comint-process-echoes is (changed to) non-nil when ESS is
>> loaded; why -- or why doesn't that happen for me?
> 
> Thanks Steve; this sounds promising.
> 
> In my .emacs file I have
> 
> ;; In Emacs 22, this has become necessary:
> (setq ess-eval-visibly-p nil)
> 
> When I change that to t, I see the password echo...  

Yup this is due to this (line 2148):

  https://github.com/emacs-ess/ESS/blob/ffc0d133547f2d86f5c0493bd519520617be2acf/lisp/ess-inf.el#L2148

This should probably be handled in a comint filter where we'd lookup
for `comint-password-prompt-regexp`. But it's a complicated regexp
so it could cause performance issues on long outputs.

Another idea: add such filter but temporarily, whenever comint
detects a password prompt.

Lionel