if err != nil {
		t.Fatal(err)
	}
	if err := r.Close(); err != nil {
		t.Fatal(err)
	}

	expect := syscall.EPIPE
	if runtime.GOOS == "windows" {
		// 232 is Windows error code ERROR_NO_DATA, "The pipe is being closed".
		expect = syscall.Errno(232)
	}
	// Every time we write to the pipe we should get an EPIPE.
	for i := 0; i < 20; i++ {
		_, err = w.Write([]byte("hi"))
		if err == nil {

to a broken pipe on some other file descriptor will take no action on
the SIGPIPE signal, and the write will fail with an EPIPE error.

If the program has called Notify to receive SIGPIPE signals, the file
descriptor number does not matter. The SIGPIPE signal will be
delivered to the Notify channel, and the write will fail with an EPIPE
error.

This means that, by default, command line programs will behave like

	return f
}

func sigpipe() // implemented in package runtime

// epipecheck raises SIGPIPE if we get an EPIPE error on standard
// output or standard error. See the SIGPIPE docs in os/signal, and
// issue 11845.
func epipecheck(file *File, e error) {
	if e == syscall.EPIPE && file.stdoutOrErr {
		sigpipe()
	}
}

// DevNull is the name of the operating system's “null device.”

	{27, "EFBIG", "file too large"},
	{28, "ENOSPC", "no space left on device"},
	{29, "ESPIPE", "illegal seek"},
	{30, "EROFS", "read-only file system"},
	{31, "EMLINK", "too many links"},
	{32, "EPIPE", "broken pipe"},
	{33, "EDOM", "numerical argument out of domain"},
	{34, "ERANGE", "numerical result out of range"},
	{35, "ENOMSG", "no message of desired type"},
	{36, "EIDRM", "identifier removed"},

	{27, "EFBIG", "file too large"},
	{28, "ENOSPC", "no space left on device"},
	{29, "ESPIPE", "illegal seek"},
	{30, "EROFS", "read-only file system"},
	{31, "EMLINK", "too many links"},
	{32, "EPIPE", "broken pipe"},
	{33, "EDOM", "numerical argument out of domain"},
	{34, "ERANGE", "numerical result out of range"},
	{35, "EDEADLK", "resource deadlock avoided"},
	{36, "ENAMETOOLONG", "file name too long"},

	{27, "EFBIG", "file too large"},
	{28, "ENOSPC", "no space left on device"},
	{29, "ESPIPE", "illegal seek"},
	{30, "EROFS", "read-only file system"},
	{31, "EMLINK", "too many links"},
	{32, "EPIPE", "broken pipe"},
	{33, "EDOM", "numerical argument out of domain"},
	{34, "ERANGE", "numerical result out of range"},
	{35, "EDEADLK", "resource deadlock avoided"},
	{36, "ENAMETOOLONG", "file name too long"},

	{27, "EFBIG", "file too large"},
	{28, "ENOSPC", "no space left on device"},
	{29, "ESPIPE", "illegal seek"},
	{30, "EROFS", "read-only file system"},
	{31, "EMLINK", "too many links"},
	{32, "EPIPE", "broken pipe"},
	{33, "EDOM", "numerical argument out of domain"},
	{34, "ERANGE", "numerical result out of range"},
	{35, "EDEADLK", "resource deadlock avoided"},
	{36, "ENAMETOOLONG", "file name too long"},

	{27, "EFBIG", "file too large"},
	{28, "ENOSPC", "no space left on device"},
	{29, "ESPIPE", "illegal seek"},
	{30, "EROFS", "read-only file system"},
	{31, "EMLINK", "too many links"},
	{32, "EPIPE", "broken pipe"},
	{33, "EDOM", "numerical argument out of domain"},
	{34, "ERANGE", "numerical result out of range"},
	{35, "EDEADLK", "resource deadlock avoided"},
	{36, "ENAMETOOLONG", "file name too long"},

	{27, "EFBIG", "file too large"},
	{28, "ENOSPC", "no space left on device"},
	{29, "ESPIPE", "illegal seek"},
	{30, "EROFS", "read-only file system"},
	{31, "EMLINK", "too many links"},
	{32, "EPIPE", "broken pipe"},
	{33, "EDOM", "numerical argument out of domain"},
	{34, "ERANGE", "numerical result out of range"},
	{35, "EDEADLK", "resource deadlock avoided"},
	{36, "ENAMETOOLONG", "file name too long"},

	{27, "EFBIG", "file too large"},
	{28, "ENOSPC", "no space left on device"},
	{29, "ESPIPE", "illegal seek"},
	{30, "EROFS", "read-only file system"},
	{31, "EMLINK", "too many links"},
	{32, "EPIPE", "broken pipe"},
	{33, "EDOM", "numerical argument out of domain"},
	{34, "ERANGE", "numerical result out of range"},
	{35, "ENOMSG", "no message of desired type"},
	{36, "EIDRM", "identifier removed"},