install/53475: Installing from NetBSD-8.0-amd64-install.img fails, system hangs at login prompt

[rwolter%web.de@localhost]

>Number:         53475
>Category:       install
>Synopsis:       Installing from NetBSD-8.0-amd64-install.img fails, system hangs at login prompt
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    install-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Jul 27 14:40:00 +0000 2018
>Originator:     Robert Wolter
>Release:        NetBSD-8.0-amd64
>Organization:
>Environment:
N/A
>Description:
I can't install from NetBSD-8.0-amd64-install.img, the system hangs at the login prompt. No keys wok, not even num lock or caps lock. I get some nouveau-related messages before. I chose all possible boot options, ACPI and SMP on and off, they always end up hanging at the login prompt. I'm still waiting to be registered by the admins at http://daemonforums.org/ so I can post photos there.
>How-To-Repeat:
Boot NetBSD-8.0-amd64-install.img from a USB stick.
>Fix: