I found another in Test::WWW::Mechanize

Test-WWW-Mechanize-1.24\t\TestServer.pm

sub new {
    my $class = shift;

    die 'An instance of TestServer has already been started.' if $pid;

    # XXX This should really be a random port.
    $class = $class->SUPER::new(13432, @_);
    $class->host('127.0.0.1');
    return $class;
}
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