Fix test-http-allow-req-after-204-res

Agent queue waits for connecting sockets.

lib/http.js

@@ -951,11 +951,17 @@ Agent.prototype._establishNewConnection = function() {
   // Grab a new "socket". Depending on the implementation of _getConnection
   // this could either be a raw TCP socket or a TLS stream.
   var socket = this._getConnection(this.host, this.port, function () {
+    socket._httpConnecting = false;
     self.emit('connect'); // mostly for the shim.
     debug("Agent _getConnection callback");
     self._cycle();
   });
 
+  // Use this special mark so that we know if the socket is connecting.
+  // TODO: come up with a standard way of specifying that a stream is being
+  // connected across tls and net.
+  socket._httpConnecting = true;
+
   this.sockets.push(socket);
 
   // Add a parser to the socket.
@@ -1109,11 +1115,14 @@ Agent.prototype._getConnection = function(host, port, cb) {
 // waiting sockets. If a waiting socket cannot be found, it will
 // start the process of establishing one.
 Agent.prototype._cycle = function() {
-  debug("Agent _cycle");
+  debug("Agent _cycle sockets=" + this.sockets.length + " queue=" + this.queue.length);
 
   var first = this.queue[0];
   if (!first) return;
 
+
+  var haveConnectingSocket = false;
+
   // First try to find an available socket.
   for (var i = 0; i < this.sockets.length; i++) {
     var socket = this.sockets[i];
@@ -1126,11 +1135,13 @@ Agent.prototype._cycle = function() {
       first.assignSocket(socket);
       return;
     }
+
+    if (socket._httpConnecting) haveConnectingSocket = true;
   }
 
-  // Otherwise see if we should be starting a new connection to handle
-  // this.
-  if (this.sockets.length < this.maxSockets) {
+  // If no sockets are connecting, and we have space for another we should
+  // be starting a new connection to handle this request.
+  if (!haveConnectingSocket && this.sockets.length < this.maxSockets) {
     this._establishNewConnection();
   }