bug#20609: 25.0.50; How to I easily generate the "action stamp" given a commit hash?

[Noam Postavsky <npostavs@gmail.com>]

Stefan Kangas <stefan@marxist.se> writes:

> Noam Postavsky <npostavs@users.sourceforge.net> writes:
>
>> I would like to propose doing away with this "action stamp" thing.  It
>> is okay for its original purpose: an almost-guaranteed-unique identifier
>> for an automated repository format conversion tool.  But it is not very
>> human-readable.  It is fairly awkward to come up with a git command that
>> comes up with the correct UTC timestamp.  We hardly use it anyway.

I can add to this, it's not entirely clear whether the timestamp is
committer or author.  https://gitlab.com/esr/reposurgeon/issues/144

>> Giving just the date (no timestamp) plus summary line should be unique
>> enough, and is very human readable.
>
> Nothing has happened here in two years,

There was some discussion on emacs-devel,
https://lists.gnu.org/r/emacs-devel/2018-07/msg00461.html

> but I think it's a good idea to get rid of action stamps and replace
> them with something that we can easily generate.  Noam's proposal
> seems to solve that.

Yeah, I'm still inclined to remove action stamps.  I guess we should
also add a way to easily generate date + summary given a commit hash
(giving the the git repo may be needed as well, e.g., for cases where
your mail buffer doesn't live in the git repository you're talking
about).