set .converters and ._encoding by hand

...revert to previous change, since always calling the constructor of
VersionedData may have unintended consequences. Instead, just set .converts and
._encoding, since they are no longer in the prototype and must be set on the
object itself.

lib/SIN.js

@@ -3,10 +3,13 @@ var EncodedData = require('../util/EncodedData');
 var util = require('util');
 
 function SIN(type, payload) {
-  SIN.super_.call(this, type, payload);
-  if (typeof type != 'number')
+  if (typeof type != 'number') {
+    SIN.super_.call(this, type, payload);
     return;
+  }
   this.data = new Buffer(1 + 1 + payload.length);
+  this.converters = this.encodings['binary'].converters;
+  this._encoding = this.encodings['binary']._encoding;
   this.encoding('binary');
   this.prefix(0x0F); // SIN magic number, in numberspace
   this.type(type);