[ruby-core:28921] Using system calls (and pthreads calls) after fork()

If I'm walking through the code correctly, it appears this happens in
several places within Ruby 1.9.  If this is the case, is this safe?

I'm running into problems running this method on NetBSD 5.0.2 (either on
32 or 64 bit, and after patching NetBSD's pthread library to properly
set an internal state variable.)

50.times do
  assert_normal_exit %q{
    at_exit { p :foo }

    megacontent = "abc" * 12345678
    #File.open("megasrc", "w") {|f| f << megacontent }

    Thread.new { sleep rand*0.2; Process.kill(:INT, $$) }

    r1, w1 = IO.pipe
    r2, w2 = IO.pipe
    t1 = Thread.new { w1 << megacontent; w1.close }
    t2 = Thread.new { r2.read }
    IO.copy_stream(r1, w2) rescue nil
    r2.close; w2.close
    r1.close; w1.close
  }, '', ["INT"] or break
end

All other threading tests pass (with the mentioned libpthread patches,
which I am about to commit to NetBSD) but this one seems to be doing too
much after fork() for NetBSD to like.

--Michael