most bizarre libc.so.7 problem

[B. Cook]

I have a machine at home that I build releng_7 on from time to time; 
about once a month or so.

yesterday I did that, and this AM I have libc.so.7 errors all over the 
place.

turns out libc.so.7 was not in /lib

I had to boot into /rescue/sh and get my zfs stuff mounted and do a 
quick cp from /usr/obj/usr/src/lib/libc/libc.so.7 to /lib/libc.so.7

then everything was fine..

do I'm doing a buildworld again while I'm here and see if something 
failed on my part..

I've been doing this for a while and never had this problem..

below is what I do..

  cat -n /root/build-world
      1  #!/bin/sh
      2  cd /usr/src
      3  make update
      4  #chflags -R noschg /usr/obj/*
      5  rm -rf /usr/obj/*
      6  mkdir /var/log/build
      7  make -j4 buildworld 2>&1 | tee /var/log/build/bworld-`date 
"+%Y%m%d-%H%M"`.log && \
      8  make -j4 buildkernel 2>&1 | tee /var/log/build/bkernel-`date 
"+%Y%m%d-%H%M"`.log && \
      9  make installkernel 2>&1 | tee /var/log/build/ikernel-`date 
"+%Y%m%d-%H%M"`.log && \
     10  make installworld  2>&1 | tee /var/log/build/iworld-`date 
"+%Y%m%d-%H%M"`.log && \
     11  date | mail -s `hostname -s` name at domain.com &&
     12  sync && \
     13  reboot

Not sure if something changed, or if something happened..

thanks in advance