bug#37978: [PATCH] guix: new command "guix time-machine"

[Ludovic Courtès]

Hi Konrad,

Konrad Hinsen <address@hidden> skribis:

> Konrad Hinsen <address@hidden> writes:
>
>> Thanks for your detailed comments, most of which I agree with, and I
>> will make the required changes.
>
> I just submitted two new patches. Looking forward to everyone's feedbck!

I’ve just applied them, thank you!

I followed up with one commit to gracefully handle Git errors (e.g.,
when one type ‘--commit=foobar’) and another one to handle build options
like the other commands.  Let me know if anything looks wrong.

Anyway, I can do things like this:

--8<---------------cut here---------------start------------->8---
$ ./pre-inst-env guix time-machine 
--commit=65956ad3526ba09e1f7a40722c96c6ef7c0936fe -- package -A |wc -l
Updating channel 'guix' from Git repository at 
'https://git.savannah.gnu.org/git/guix.git'...
guile: warning: failed to install locale
warning: failed to install locale: Invalid argument
7666
--8<---------------cut here---------------end--------------->8---

… where the commit in question is from June 2018.  Pretty fun!

It would be neat if the “Updating…” message wouldn’t show up when in
fact everything is already available.  Also, it’d be nice if we could
write (and in ‘guix pull’ too) ‘--date=2019-07-07’ or
‘--date=last-month’.  Future work!  :-)

Thanks again for this nifty command!

Ludo’.