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

[Dmitry Gutov]

Hi Juri,

The approach LGTM. I'd have used "describe" or "show", but it's not 
important. Some minor nits:

On 20.11.2019 23:50, Juri Linkov wrote:
>      (setq default-directory rootdir)

This probably needs a saving (let ((default-directory 
default-directory)) ...) above it.

> +With a prefix argument, ask for a command to run that will output
> +the revision information."

This sentence should be into the docstring of the new command, not in 
the backend implementation.

> +                      (read-shell-command
> +                        "Show revision with command: "
> +                        (format "%s %s" vc-git-program
> +                                (mapconcat 'identity args " "))
> +                        'vc-git-history)
> +                      " " t))))

If wonder if some user someday is going to try and input there something 
that doesn't start with 'git '.