Actually, this issue is already fixed with NetBSD 6.1. Thank you for tracking this PR even though it was submitted three years ago.
You could close this ticket now.
At 2015-09-09 14:33:49, dholland%NetBSD.org@localhost wrote:
>Synopsis: NetBSD installation CD failed to boot
>
>State-Changed-From-To: open->feedback
>State-Changed-By: dholland%NetBSD.org@localhost
>State-Changed-When: Wed, 09 Sep 2015 06:33:49 +0000
>State-Changed-Why:
>If you still have this hardware and still care about this problem, please
>try the 7.0 release candidate (or the 7.0 release if it appears before you
>get to it) as with luck the problem's fixed there.
>
>If you don't, let us/me know and I'll close the ticket.
>
>
>