test/ruby/test_io.rb (test_recycled_fd_close): remove hacks

I think I finally fixed the underlying bug in r65937
("io.c (fptr_finalize_flush): close race leading to EBADF")

I've run this test over 100000 times on a multicore system, now.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66104 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/ruby/test_io.rb

@@ -3774,14 +3774,6 @@ __END__
             th = Thread.new { r.read(1) }
             w.write(dot)
 
-            # XXX not sure why this is needed on Linux, otherwise
-            # the "good" reader thread doesn't always join properly
-            # because the reader never sees the first write
-            if RUBY_PLATFORM =~ /linux/
-              # assert_equal can fail if this is another char...
-              w.write(dot)
-            end
-
             assert_same th, th.join(15), '"good" reader timeout'
             assert_equal(dot, th.value)
           end
@@ -3800,9 +3792,6 @@ __END__
           end
           Thread.pass until th.stop?
 
-          # XXX not sure why, this reduces Linux CI failures
-          assert_nil th.join(0.001)
-
           r.close
           assert_same th, th.join(30), '"bad" reader timeout'
           assert_match(/stream closed/, th.value.message)