Changed the comment on lines 53-54, fixing issue 8927

lib/child_process.js

@@ -50,8 +50,8 @@ exports.fork = function(modulePath /*, args, options*/) {
   args = execArgv.concat([modulePath], args);
 
   if (!Array.isArray(options.stdio)) {
-    // Leave stdin open for the IPC channel. stdout and stderr should be the
-    // same as the parent's if silent isn't set.
+    // Use a separate fd=4 for IPC channel. Inherit stdin, stdout and stderr 
+    // from the parent if silent isn't set.
     options.stdio = options.silent ? ['pipe', 'pipe', 'pipe', 'ipc'] :
         [0, 1, 2, 'ipc'];
   } else if (options.stdio.indexOf('ipc') === -1) {