install/57927: sysinst gpt editor loses partition options, can't change options for one partition at a time

[campbell+netbsd%mumble.net@localhost]

>Number:         57927
>Category:       install
>Synopsis:       sysinst gpt editor loses partition options, can't change options for one partition at a time
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    install-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Feb 11 20:10:00 +0000 2024
>Originator:     Taylor R Campbell
>Release:        10.0_RC4
>Organization:
The NetBSD Foundinst
>Environment:
>Description:
Someone on Mastodon reports:

> - If I create a new GPT partition and set options for it, sysinst will forget those options after I set them once I leave the menu.
> 
> - sysinst will set the options for partition 2 to be the same as partition 1 after I change them.
> 
> My workaround was to Ctrl-C to exit sysinst, create the partitions manually on the command line using gpt (which no longer segfaults, unlike in the 9.3 install image), and create the filesystems manually. It took two tries in sysinst after that, but it found the correct partitions and worked after that.
>How-To-Repeat:
As in description.  I haven't reproduced the problem, just filing this so we can track reproduction/diagnosis/fix.
>Fix: