events: Don't clobber pre-existing _events obj in EE ctor

lib/events.js

@@ -31,8 +31,8 @@ function EventEmitter() {
       this.domain = domain.active;
     }
   }
-  this._events = null;
-  this._maxListeners = defaultMaxListeners;
+  this._events = this._events || null;
+  this._maxListeners = this._maxListeners || defaultMaxListeners;
 }
 exports.EventEmitter = EventEmitter;
 

test/simple/test-event-emitter-subclass.js

@@ -0,0 +1,43 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var common = require('../common');
+var assert = require('assert');
+var EventEmitter = require('events').EventEmitter;
+var util = require('util');
+
+util.inherits(MyEE, EventEmitter);
+
+function MyEE(cb) {
+  this.on('foo', cb);
+  process.nextTick(this.emit.bind(this, 'foo'));
+  EventEmitter.call(this);
+}
+
+var called = false;
+var myee = new MyEE(function() {
+  called = true;
+});
+
+process.on('exit', function() {
+  assert(called);
+  console.log('ok');
+});