Fix socket error handling during client unbind

The client now blackholes any socket errors after sending an unbind.
This prevents servers which issue RST from causing unecessary errors for
what was a succesful operation.

Fix mcavage/node-ldapjs#217

lib/client/client.js

@@ -853,9 +853,6 @@ Client.prototype.unbind = function unbind(callback) {
     return callback();
 
   var req = new UnbindRequest();
-  if (this.socket.listeners('error').length === 0) {
-    this.socket.once('error', function () {});
-  }
   return this._send(req, 'unbind', null, callback);
 };
 
@@ -1343,6 +1340,10 @@ Client.prototype._sendSocket = function _sendSocket(message,
       conn.unbindMessageID = message.id;
       // Mark client as disconnected once unbind clears the socket
       self.connected = false;
+      // Some servers will RST the connection after receiving an unbind.
+      // Socket errors are blackholed since the connection is being closed.
+      conn.removeAllListeners('error');
+      conn.on('error', function () {});
       conn.end();
     } else if (emitter) {
       sentEmitter = true;