Node 0.8 child_processes can't use /dev/stdin or /proc/self/fd/N

cat_test.js

var spawn = require('child_process').spawn;

var cp = spawn('cat', ['/proc/self/fd/0']);

cp.stdout.setEncoding('utf8');
cp.stdout.on('data', function (chunk) {
    console.log("child stdout: ", chunk);
});

cp.stderr.setEncoding('utf8');
cp.stderr.on('data', function (chunk) {
    console.log("child stderr: ", chunk);
});

cp.on('exit', function (code) {
    console.log("exit code", code);
});

cp.stdin.end();

node 0.6.17 output

$ node cat_test.js
exit code 0

node 0.8.9 output

$ node spidertest.js
exit code 1
child stderr:  cat: /proc/self/fd/0: No such device or address

pipetest.c

#include <sys/types.h>
#include <sys/socket.h>
#include <fcntl.h>
#include <sys/wait.h>
#include <stdio.h>
#include <unistd.h>

int main(int argc, char** argv) {
  int pipefd[2];
  int fd;
  /*if (socketpair(AF_UNIX, SOCK_STREAM, 0, pipefd) != 0) {                                                                                                                                               
    perror("socketpair"); return 1;                                                                                                                                                                       
  }*/
  if (pipe2(pipefd, O_CLOEXEC) != 0) {
    perror("pipe2"); return 1;
  }
  if (dup2(pipefd[0], 0) == -1) {
    perror("dup2"); return 1;
  }
  fd = open("/proc/self/fd/0", O_RDONLY);
  if (fd == -1) {
    perror("open"); return 1;
  } else {
    printf("opened %d\n", fd);
    return 0;
  }
}

why

Node 0.8 changes libuv to use socketpair instead of pipe2 to create the pipe
between parent and child.
See https://github.com/joyent/libuv/commit/c0081f0e6675131721dbb5138fd398792a8c2163

But when you use socketpair, this breaks the use of /dev/stdin or /proc/self/fd/0 (etc).

See even just the C file below: if you replace the pipe2 call with the socketpair call, the open fails.

why?

Node 0.8 changes libuv to use socketpair instead of pipe2 to create the pipe between parent and child. See https://github.com/joyent/libuv/commit/c0081f0e6675131721dbb5138fd398792a8c2163

But when you use socketpair, this breaks the use of /dev/stdin or /proc/self/fd/0 (etc).