$ cd HTML-Tagset-3.10

$ make test
/usr/bin/perl.exe "-MExtUtils::Command::MM" "-e" "test_harness(0, 'blib/lib', 'blib/arch')" t/*.t
t/00_about_verbose....ok
t/01_old_junk.........ok
t/pod.................                <--- hangs

# the test succeeds without Test::Harness
$ perl -I `pwd`/blib/lib -T t/pod.t
1..1
ok 1 - blib/lib/HTML/Tagset.pm

$ PERLDB_OPTS="AutoTrace=1 NonStop=1 Frame=2" perl -MExtUtils::Command::MM -de
"test_harness(0, 'blib/lib', 'blib/arch')" t/*.t
...

      entering Test::Harness::Straps::_reset_file_state
       605:         my($self) = shift;
       607:         delete @{$self}{qw(max skip_all todo too_many_tests)};
       607:         delete @{$self}{qw(max skip_all todo too_many_tests)};
       608:         $self->{line}       = 0;
       609:         $self->{saw_header} = 0;
       610:         $self->{saw_bailout}= 0;
       611:         $self->{lone_not_line} = 0;
       612:         $self->{bailout_reason} = '';
       613:         $self->{'next'}       = 1;
      exited Test::Harness::Straps::_reset_file_state
      119:          $self->{file} = $name;
      120:          my %totals  = (
      121:                         max      => 0,
      122:                         seen     => 0,
      133:          $self->{totals}{$name}         = \%totals;
      134:          while( defined(my $line = $it->next) ) {
      entering Test::Harness::Iterator::FH::next
       57:          my $fh = $_[0]->{fh};
       60:          return scalar <$fh>;   <-- ultimately hangs here