http: OutgoingMessage change writable after end

When an OutgoingMessage is closed (for example, using the `end`
method), its 'writable' property should be changed to false - since it
is not writable anymore. The 'writable' property should have the
opposite value of the 'finished' property.

lib/_http_outgoing.js

@@ -793,6 +793,7 @@ OutgoingMessage.prototype.end = function end(chunk, encoding, callback) {
     this.connection.uncork();
 
   this.finished = true;
+  this.writable = false;
 
   // There is the first message on the outgoing queue, and we've sent
   // everything to the socket.

test/parallel/test-http-outgoing-finish-writable.js

@@ -0,0 +1,26 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const http = require('http');
+
+const server = http.createServer(common.mustCall(function(req, res) {
+  assert(res.writable, 'Res should be writable when it is received \
+                          and opened.');
+  assert(!res.finished, 'Res shouldn\'t be finished when it is received \
+                          and opened.');
+  res.end();
+  assert(!res.writable, 'Res shouldn\'t be writable after it was closed.');
+  assert(res.finished, 'Res should be finished after it was closed.');
+
+  server.close();
+}));
+
+server.listen(0);
+
+server.on('listening', common.mustCall(function() {
+  http.request({
+    port: server.address().port,
+    method: 'GET',
+    path: '/'
+  }).end();
+}));

test/parallel/test-pipe-outgoing-message-data-emitted-after-ended.js

@@ -0,0 +1,35 @@
+'use strict';
+const common = require('../common');
+const http = require('http');
+const OutgoingMessage = require('_http_outgoing').OutgoingMessage;
+
+const server = http.createServer(common.mustCall(function(req, res) {
+  console.log('Got a request, piping an OutgoingMessage to it.');
+  const outgointMessage = new OutgoingMessage();
+  outgointMessage.pipe(res);
+
+  setTimeout(() => {
+    console.log('Closing response.');
+    res.end();
+    outgointMessage.emit('data', 'some data');
+
+    // If we got here - 'write after end' wasn't raised and the test passed.
+    setTimeout(() => server.close(), 10);
+  }, 10);
+
+  setInterval(() => {
+    console.log('Emitting some data to outgointMessage');
+    outgointMessage.emit('data', 'some data');
+  }, 1).unref();
+
+}));
+
+server.listen(0);
+
+server.on('listening', common.mustCall(function() {
+  http.request({
+    port: server.address().port,
+    method: 'GET',
+    path: '/'
+  }).end();
+}));