As usual, ATF is actively interfering with test debugging. Almost all
runs in the past few days have failed this test with "stdout not
empty". In one run it timed out:
http://releng.netbsd.org/b5reports/i386/build/2016.11.22.06.51.14/test.html
but in this case ATF helpfully suppressed the log data.
Maybe if someone can figure out how to make the test hang reliably
then they can turn the logging on again and run it outside of ATF to
see what's happening.
In the meantime this problem is not likely to get fixed until we have
a less obstructive testing framework.