Hello! This is just an idea.
Is it possible to automatize detection of this kind of problems? 
As I see, some PC can has crontab job to do `guix pull`, so that if 'Backtrace' message occurs, it sends a report to developer not to rush up to push his branch to master branch.
Different branches can be defended from such a minor issues, just trying `guix pull` for all branches using channels. 


Dec 7, 2018, 2:15 PM by ludo@gnu.org:

> Hi Diego,
>
> Diego Nicola Barbato <> dnbarbato@posteo.de <mailto:dnbarbato@posteo.de>> > skribis:
>
>> When I run ‘guix system roll-back’ I get the following backtrace:
>>
>
> Fixed in commit 6ddc63e599a26c302f74d0622f67cfd987f0dc5f, thanks!
>
> Ludo'.
>