Hello,

I tried the 1.2.0 graphical installer at ae0fe28, installing Guix System
from a usb drive to another one.

I had three issues:

* The auto partitioning crashed, backtrace as attachment.

* Using manual partitioning as a work-around, I started the installation
and observed that the installer downloaded "python" sources and then
substitutes for the whole bootstrapping chain (also as attachment).

* The substitutes download speed was sometimes super low (~ 50Kb/s).

An unpleasant sunday afternoon testing :(.

Mathieu