bug#19045: 25.0.50; [PATCH] vc-git-print-log use --follow

[Juri Linkov <juri@linkov.net>]

>> > Too bad that a new useful customizable variable
>> > vc-git-print-log-follow is not mentioned in NEWS.26.
>> >
>> > It works quite well, but only with the following fix
>> > that puts more restrictions - it checks not only
>> > for a directory, but also if it is a single file.
>> >
>> > The whole patch is intended for the emacs-26 branch:
>> 
>> Pushed to the emacs-26 branch.
>
> Please don't push anything to the release branch without John's or
> mine explicit approval.  As things are, I'm very busy these days, and
> didn't yet have time to review the patch thoroughly, so I'm not sure
> I'm happy with its being pushed.

Sorry, will wait more time the next time.

>> diff --git a/lisp/vc/vc-dispatcher.el b/lisp/vc/vc-dispatcher.el
>> index b0d2221..efdd29e 100644
>> --- a/lisp/vc/vc-dispatcher.el
>> +++ b/lisp/vc/vc-dispatcher.el
>> @@ -313,6 +313,8 @@ vc-do-command
>>  	    (status 0))
>>  	(when files
>>  	  (setq squeezed (nconc squeezed files)))
>> +        (let ((inhibit-message t))
>> +          (message "Running %s %s" command (vc-delistify squeezed)))
>>  	(let (;; Since some functions need to parse the output
>>  	      ;; from external commands, set LC_MESSAGES to C.
>>  	      (process-environment (cons "LC_MESSAGES=C" process-environment))
>
> I don't understand why would we want to hard-code the fact that these
> commands are not shown in the echo area.

I don't want to cause more flicker in the echo area when the full command
gets overwritten immediately by the truncated command in the echo area.