Allow log.child(...) to work even if the logger is a *sub-class* of Bunyan's Logger class.

CHANGES.md

@@ -8,6 +8,8 @@ Known issues:
 
 ## bunyan 1.3.4 (not yet released)
 
+- Allow `log.child(...)` to work even if the logger is a *sub-class*
+  of Bunyan's Logger class.
 - [issue #219] Hide 'source-map-support' require from browserify.
 - [issue #218] Reset `haveNonRawStreams` on `<logger>.addStream`.
 

lib/bunyan.js

@@ -608,7 +608,7 @@ Logger.prototype.addSerializers = function addSerializers(serializers) {
  *    creation. See 'tools/timechild.js' for numbers.
  */
 Logger.prototype.child = function (options, simple) {
-    return new Logger(this, options || {}, simple);
+    return new (this.constructor)(this, options || {}, simple);
 }