Fix piping to process.stdout and process.stderr

process.stdout and process.stderr are not closed or ended after piping
like other streams. So we must resolve them manually.

index.js

@@ -5,6 +5,14 @@ var Q = require("q");
 function promiseFromStreams(streams) {
     return Q.all(streams.map(function(stream) {
         return Q.promise(function(resolve, reject) {
+
+            // process.stdout and process.stderr are not closed or ended
+            // after piping like other streams. So we must resolve them
+            // manually.
+            if (stream === process.stdout || stream === process.stderr) {
+                return resolve();
+            }
+
             stream.on("error", function(streamErr) {
                 var err = new Error(streamErr.message);
                 err.source = stream;

test.js

@@ -53,6 +53,15 @@ describe("promisePipe", function() {
         });
     });
 
+    ["stdout", "stderr"].forEach(function(stdio) {
+        it("can pipe to " + stdio, function(done) {
+            var input = fs.createReadStream(INPUT);
+            promisePipe(input, process[stdio]).done(function() {
+                done();
+            });
+        });
+    });
+
     it("can handle errors from source", function(done) {
         var input = fs.createReadStream("bad");
         var output = fs.createWriteStream(OUTPUT);