bug#46829: Fresh install of 1.2.0 can't guix pull

[Leo Famulari]

On Mon, Apr 12, 2021 at 02:25:11PM +0200, Ludovic Courtès wrote:
> Could you grab a backtrace, with:
> 
>   gdb $(which guile) core

I don't know where to find this 'core' file. I'm on Guix System (the
Berlin server).