I'm fairly new at using the build.sh tools, but slavishly following the 
"Tracking NetBSD-current" http://netbsd.org/Documentation/current/

I just had a problem where I built and installed a new kernel, then 
was building userland -- and sshd went away during the build. 

I have no idea why.  But, I'm thinking that there was something that 
changed between June 11 and June 16 that affected userland.

The build order as shown is:
 (1) build tools
 (2) build kernel
 (3) install kernel
 (4) reboot
 (5) build userland
 (6) install userland
 (7) reboot

I'm thinking that it might be better to move (5) immediately after (2). 
That way, the window for userland incompatibilities would be smaller. 

Is there a subtle reason why a new kernel must be installed before 
building a new userland?

My suggestion would be closer to an install from distribution, where
both kernel and userland are already built.

-- 
William Allen Simpson
    Key fingerprint =  17 40 5E 67 15 6F 31 26  DD 0D B9 9B 6A 15 2C 32