some.patch

commit 91a46a2a953bd28d534a768968e82355e42b9714
Author: Tj Holowaychuk <tj@vision-media.ca>
Date:   Thu Feb 10 16:29:34 2011 -0800

    Fixed field merging with progressive fields on writeHead()

diff --git a/lib/http.js b/lib/http.js
index 9506a8c..e109d0b 100644
--- a/lib/http.js
+++ b/lib/http.js
@@ -754,7 +754,7 @@ ServerResponse.prototype.writeContinue = function() {
 };
 
 ServerResponse.prototype._implicitHeader = function() {
-  this.writeHead(this.statusCode, this._renderHeaders());
+  this.writeHead(this.statusCode);
 };
 
 ServerResponse.prototype.writeHead = function(statusCode) {
@@ -769,9 +769,33 @@ ServerResponse.prototype.writeHead = function(statusCode) {
   }
 
   if (typeof arguments[headerIndex] == 'object') {
-    headers = arguments[headerIndex];
+    // slow-case merge giving precedence to
+    // header fields passed to this method
+    headers = this._renderHeaders();
+    var obj = arguments[headerIndex];
+
+    // handle array case
+    // TODO: remove when array is no longer accepted
+    if (Array.isArray(obj)) {
+      var field;
+      for (var i = 0, len = obj.length; i < len; ++i) {
+        field = obj[i][0];
+        if (field in headers) {
+          obj.push([field, headers[field]]);
+        }
+      }
+      headers = obj;
+    // handle object case
+    } else {
+      var keys = Object.keys(obj),
+        len = keys.length;
+      for (var i = 0; i < len; ++i) {
+        headers[keys[i]] = obj[keys[i]];
+      }
+    }
   } else {
-    headers = {};
+    // fast-case
+    headers = this._renderHeaders();
   }
 
   var statusLine = 'HTTP/1.1 ' + statusCode.toString() + ' ' +
diff --git a/test/simple/test-http-mutable-headers.js b/test/simple/test-http-mutable-headers.js
index 8b44cd0..218c372 100644
--- a/test/simple/test-http-mutable-headers.js
+++ b/test/simple/test-http-mutable-headers.js
@@ -48,6 +48,12 @@ var s = http.createServer(function(req, res) {
       res.setHeader('transfer-encoding', 'chunked');
       assert.equal(res.getHeader('Transfer-Encoding'), 'chunked');
       break;
+
+    case 'writeHead':
+      res.statusCode = 404;
+      res.setHeader('x-foo', 'keyboard cat');
+      res.writeHead(200, { 'x-foo': 'bar', 'x-bar': 'baz' });
+      break;
   }
 
   res.statusCode = 201;
@@ -92,6 +98,13 @@ function nextTest () {
 
       case 'transferEncoding':
         assert.equal(response.headers['transfer-encoding'], 'chunked');
+        test = 'writeHead';
+        break;
+      
+      case 'writeHead':
+        assert.equal(response.headers['x-foo'], 'bar');
+        assert.equal(response.headers['x-bar'], 'baz');
+        assert.equal(200, response.statusCode);
         test = 'end';
         break;
 
@@ -114,6 +127,6 @@ function nextTest () {
 
 
 process.on('exit', function() {
-  assert.equal(3, testsComplete);
+  assert.equal(4, testsComplete);
 });