Solaris 9 has a kernel race condition which causes the final output written to the slave side of a pty to be lost upon the final close() of the slave device. This causes the dejagnu-based tests to fail intermittently. A workaround exists, but requires some help from the scheduler, and the "make check" must be executed from a shell with elevated priority limits.
Run something like
priocntl -s -c FX -m 30 -p 30 -i pid nnnn
as root, where nnnn is the pid of the shell whose priority
limit you wish to raise.
Sun has released kernel patches for this race condition. Apply patch 117171-11 for sparc, or patch 117172-11 for x86. Later revisions of the patches should also work. It is not necessary to run "make check" from a shell with elevated priority limits once the patch has been applied.