bug#56545: guix time-machine/shell throws "unsupported manifest format" error

[Maxim Cournoyer]

Hi Ludovic,

Ludovic Courtès <ludo@gnu.org> writes:

> Hi!
>
> Maxim Cournoyer <maxim.cournoyer@gmail.com> scribes:
>
>> and the channels.scm file:
>>
>> (list (channel
>>        (inherit %default-guix-channel)
>>        (commit
>>         "ceeb2bfcaeb4380e01d26c8425e28b94ac13558a"))) ;2022-06-07
>>
>>
>> and was surprised to be greeted with the following error:
>>
>> (repl-version 0 1 1)
>> (exception %exception (non-self-quoting 140737300283024 "#<&message message: 
>> \"unsupported manifest format\">"))
>> /var/log/guix/drvs/j8/0wjfx7s7nxhcn0wjxfysnnv2knx0c1-guix-package-cache.drv 
>> (END)
>>
>> What does it mean?  Which manifest is it referring to?
>
> Commit 4ff12d1de7cd617b791996ee7ca1240660b4c20e introduced that bug,
> which was fixed in c9fbd40785a99e13a59d8e530830ce85220a9871:
>
>   https://issues.guix.gnu.org/56441
>
> ‘guix describe’ should show that you’re using a commit in that range.
>
> The solution is to run ‘time-machine’ from a commit outside that range,
> for instance with:
>
>   guix time-machine -- time-machine -C channels.scm -- whatever
>
> :-)

That's a happy resolution.  Thank you!

Maxim