install/55752: sparc install fails with sysinst assertion failure

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         55752
>Category:       install
>Synopsis:       sparc install fails with sysinst assertion failure
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    install-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Oct 25 17:45:00 +0000 2020
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current, source date >= 2020.10.24.15.16.39
>Organization:
>Environment:
System: NetBSD
Architecture: sparc
Machine: sparc
>Description:

On the TNF sparc testbed, installation is currently failing with:

  assertion "e == n" failed: file "/tmp/build/2020.10.24.16.13.15-sparc/src/usr.sbin/sysinst/arch/sparc/../../util.c", line 528, function "get_available_cds"
  [1]   Abort trap (core dumped) /sysinst

The problem started with this commit:

  2020.10.24.16.13.15 martin src/usr.sbin/sysinst/menus.mi 1.22
  2020.10.24.16.13.15 martin src/usr.sbin/sysinst/msg.mi.de 1.25
  2020.10.24.16.13.15 martin src/usr.sbin/sysinst/msg.mi.en 1.33
  2020.10.24.16.13.15 martin src/usr.sbin/sysinst/msg.mi.es 1.27
  2020.10.24.16.13.15 martin src/usr.sbin/sysinst/msg.mi.fr 1.32
  2020.10.24.16.13.15 martin src/usr.sbin/sysinst/msg.mi.pl 1.33
  2020.10.24.16.13.15 martin src/usr.sbin/sysinst/util.c 1.49

Logs:

  http://releng.netbsd.org/b5reports/sparc/commits-2020.10.html#2020.10.24.16.13.15

>How-To-Repeat:

>Fix: