Add 2 lengths of shrink-tube on the 2 wires.

Now, solder the 4 wires together.

Make sure to connect white to white, and black to the bare metal one.

Make sure to do this step really quickly, as the heat-shrink tube will contract from the heat of the soldering.

Alternatively, you could just use duct tape—just be careful so it doesn't slide off when you're bending the wires.

Move the shirk-tube over the soldering spots, and heat it up. (Mine fell a bit short, so I did end up using a bit of duct tape.)