🚀 go-pugleaf

I encountered the following problem with emacs 19.25 on goldman.gnu.ai.mit.edu.

When I link a shell history file, like ~/.bash_history, to /dev/null,
and then do M-x shell, I get an error indicating that my history file
is not a regular file, and the *shell* buffer, while it starts, is not
visible.

The problem appears to be in the function shell-mode in shell.el. There
is code like this to test the history file to see if it is /dev/null:

    (setq comint-input-ring-file-name
	  (or (getenv "HISTFILE")
	      (cond ((string-equal shell "bash") "~/.bash_history")
		    ((string-equal shell "ksh") "~/.sh_history")
		    (t "~/.history"))))
    (if (equal comint-input-ring-file-name "/dev/null")
	(setq comint-input-ring-file-name nil))

I think that something like this will work better:

    (setq comint-input-ring-file-name
	  (or (getenv "HISTFILE")
	      (cond ((string-equal shell "bash") "~/.bash_history")
		    ((string-equal shell "ksh") "~/.sh_history")
		    (t "~/.history"))))
    (if (equal (file-truename (expand-file-name
			       comint-input-ring-file-name)) "/dev/null")
	(setq comint-input-ring-file-name nil))