I have set TOOLDIR to /usr/obj/tools and invoke build.sh like this:

  TOOLDIR=/usr/obj/tools; export TOOLDIR
  TOOLSBIN=$TOOLDIR/bin

  DESTDIR=/usr/obj/$arch/destdir

  cd src && ./build.sh -t -T $TOOLDIR -u || exit 1)

Also in /etc/mk.conf:

  MKOBJDIRS=yes
  MAKEOBJDIRPREFIX=/usr/obj

During the tools build, the install fails with:

install ===> groff
/usr/obj/tools/bin/nbinstall -c -p -r -m 444 /usr/home/gdt/QUIST-current/netbsd/src/tools/groff/../../share/tmac/andoc /usr/obj/tools/share/groff/tmac/tmac.and
oc
nbinstall: /usr/obj/tools/share/groff/tmac: mkstemp: No such file or directory
*** Error code 1

and it seems that the /usr/obj/tools/share/groff directory does not
have a tmac subdir.

The other build lines seem to do 'mkdir -p' before installs.

This only happens on sparc, and I have tried rm'ing my whole /usr/obj
first.
After mkdir'ing the offending directory, I ran build.sh again (as
above), and got

/usr/obj/tools/bin/nbinstall -c -p -r -m 444 /usr/home/gdt/QUIST-current/netbsd/src/tools/groff/../../share/tmac/andoc /usr/obj/tools/share/groff/tmac/tmac.andoc
/usr/obj/tools/bin/nbinstall -c -p -r -m 444 /usr/home/gdt/QUIST-current/netbsd/src/tools/groff/../../share/tmac/doc /usr/obj/tools/share/groff/tmac/tmac.doc
/usr/obj/tools/bin/nbinstall -c -p -r -m 444 /usr/home/gdt/QUIST-current/netbsd/src/tools/groff/../../share/tmac/doc-ditroff /usr/obj/tools/share/groff/tmac/tmac.doc-ditroff
/usr/obj/tools/bin/nbinstall -c -p -r -m 444 /usr/home/gdt/QUIST-current/netbsd/src/tools/groff/../../share/tmac/doc-common /usr/obj/tools/share/groff/tmac/tmac.doc-common
/usr/obj/tools/bin/nbinstall -c -p -r -m 444 /usr/home/gdt/QUIST-current/netbsd/src/tools/groff/../../share/tmac/doc-nroff /usr/obj/tools/share/groff/tmac/tmac.doc-nroff
/usr/obj/tools/bin/nbinstall -c -p -r -m 444 /usr/home/gdt/QUIST-current/netbsd/src/tools/groff/../../share/tmac/doc-syms /usr/obj/tools/share/groff/tmac/tmac.doc-syms
/usr/obj/tools/bin/nbinstall -c -p -r -m 444 /usr/home/gdt/QUIST-current/netbsd/src/tools/groff/../../share/tmac/doc2html /usr/obj/tools/share/groff/tmac/tmac.doc2html
/usr/obj/tools/bin/nbinstall -c -p -r -m 444 /usr/home/gdt/QUIST-current/netbsd/src/tools/groff/../../gnu/dist/groff/tmac/tmac.an /usr/obj/tools/share/groff/tmac/tmac.an.old
/usr/obj/tools/bin/nbinstall -c -p -r -m 444 /usr/obj/tools/share/groff/tmac/tmac.andoc /usr/obj/tools/share/groff/tmac/tmac.an
nbmake: don't know how to make /usr/obj/tools/lib/groff/eqn. Stop

nbmake: stopped in /usr/home/gdt/QUIST-current/netbsd/src/tools/groff
*** Error code 2

Stop.
nbmake: stopped in /usr/home/gdt/QUIST-current/netbsd/src/tools/groff
*** Error code 1

Stop.
nbmake: stopped in /usr/home/gdt/QUIST-current/netbsd/src/tools


any clues?