Some tests in the testsuite will emit a line that doesn't end with a
newline, right before we're about to output "ok" or "not ok". This
breaks the TAP output with "Tests out of sequence" errors since a TAP
harness can't understand this:
ok 1 - A test
[some output here]ok 2 - Another test
ok 3 - Yet another test
Work around it by emitting an empty line before we're about to say
"ok" or "not ok", but only if we're running under --verbose and
HARNESS_ACTIVE=1 is set, which'll only be the case when running under
a harnesses like prove(1).
I think it's better to do this than fix each tests by adding `&& echo'
everywhere. More tests might be added that break TAP in the future,
and a human isn't going to look at the extra whitespace, since
HARNESS_ACTIVE=1 always means a harness is reading it.