http: fix free http-parser too early

when the status code is 100 (Continue).

Fixes #2636.

lib/http.js

@@ -1169,7 +1169,11 @@ ClientRequest.prototype.onSocket = function(socket) {
           socket.destroy();
         }
         freeParser();
-      } else if (parser.incoming && parser.incoming.complete) {
+      } else if (parser.incoming && parser.incoming.complete &&
+                 // When the status code is 100 (Continue), the server will
+                 // send a final response after this client sends a request
+                 // body. So, we must not free the parser.
+                 parser.incoming.statusCode !== 100) {
         freeParser();
       }
     };

test/simple/test-http-expect-continue.js

@@ -44,7 +44,9 @@ server.on('checkContinue', function(req, res) {
   common.debug('Server got Expect: 100-continue...');
   res.writeContinue();
   sent_continue = true;
-  handler(req, res);
+  setTimeout(function() {
+    handler(req, res);
+  }, 100);
 });
 server.listen(common.PORT);