bug#38044: 27.0.50; There should be an easier way to look at a specific vc commit

[Eli Zaretskii]

> Cc: juri@linkov.net, larsi@gnus.org, stephen.berman@gmx.net,
>  38044@debbugs.gnu.org
> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Thu, 21 Nov 2019 21:08:49 +0200
> 
> "As I said before", when a revision is created, we fill in a number of 
> different fields, most importantly, the commit message. That's in every 
> VCS except some ancient ones. So to show a revision means to show all 
> that stuff.

Here's an alternative proposal.  It seems like almost all VCS backends
we support provide a variant of a "log" command that shows the diffs
together with the usual meta-data shown by "log".  Only RCS and CVS
don't have such an option of "log", all the rest do (most of them via
"log -p").

So we could make this a subcommand of vc-log, more accurately
vc-print-root-log, such that "C-u C-u C-x v L" will prompt for a
revision ID, and display the information produced by such a "log -p"
command (and fall back to displaying just the diffs for RCS and CVS).

Does this sound better?