bug#3717: M-x man completion

[Eli Zaretskii]

> From: Kevin Ryde <user42@zip.com.au>
> Date: Wed, 25 Nov 2009 09:58:09 +1100
> Cc: 3717@emacsbugs.donarmstrong.com, jidanni@jidanni.org
> 
> -        (call-process "man" nil '(t nil) nil "-k" (concat "^" string))
> +     (let ((process-connection-type nil) ;; pipe
> +           (process-environment (copy-sequence process-environment)))
> +       (setenv "COLUMNS" "999") ;; don't truncate long names
> +       (call-process "man" nil '(t nil) nil "-k" (concat "^" string)))

This needs to deal with versions of `man' that don't support the -k
switch.