Cluster module issue in Node.js 0.4.12

I'm setting up a Vagrant environment to do some work on a project that uses an older version of Node.js. I've been working my way through various hiccups and have reached one that has me a little stuck. The project uses the Cluster module (before it was core, I assume) and when I try to start the Node server, I get this:

$ node /vagrant/node/bin/server.js
  info - worker 0 spawned
  info - worker 1 spawned
  info - listening for connections
  info - master started
uncaughtException
{ stack: [Getter/Setter],
  arguments: undefined,
  type: undefined,
  message: 'Non-socket exists at  /vagrant/node/cluster.repl' }
  warning - kill(SIGKILL)
Error: Non-socket exists at  /vagrant/node/cluster.repl
    at net.js:1054:17
  debug - exit

Google doesn't have much to offer unless my Google Fu has been very weak for the last 24 hours.

Here's the code that starts the server:

server = cluster(server)
 .use(cluster.repl(root + '/cluster.repl'))
 .use(cluster.stats({connections: true, requests: true}))
 .use(cluster.reload(root))
 .listen(port)

Anyone have any idea what might be going on?