I last successfully built 1.5_BETA from cvs on Oct 18. Yesterday I did
another update, and make build. The build churned away for about 4
hours, got into the install part, and bombed out right after
installing libexec/ld.elf_so:

  install ===> libexec/ld.aout_so
  install -r  -c   -o root  -g wheel  -m 555  ld.so /usr/libexec/ld.so
  install -r  -c   -o root -g wheel -m 444 /drive2/src/src/libexec/ld.aout_so/rtld.1 /usr/share/man/man1/rtld.1
  /usr/share/man/man1/ld.so.1 -> /usr/share/man/man1/rtld.1
  install -r  -c   -o root -g wheel -m 444 rtld.cat1 /usr/share/man/cat1/rtld.0
  /usr/share/man/cat1/ld.so.0 -> /usr/share/man/cat1/rtld.0
  install ===> libexec/ld.elf_so
  install -r  -c    -o root -g wheel -m 555 ld.elf_so /usr/libexec/ld.elf_so
  install ===> libexec/lfs_cleanerd
  Segmentation fault - core dumped
  *** Error code 139

  Stop.
  *** Error code 1

  Stop.
  *** Error code 1

  Stop.

After this point, the system was effectively dead until I plugged the
disk in as secondary with a backup disk as primary, and copied an Oct
18th /usr/libexec back.

Just to make sure it wasn't a problem with running on an older kernel
(it had also been built on Oct 18), I built a new kernel and installed
it, then tried again (after another cvs update to make sure there was
nothing new or locally modified) - same result.

Any ideas?