code: function loadUid (cb) {
    // if we're not in unsafe-perm mode, then figure out who
    // to run stuff as.  Do this first, to support `npm update npm -g`
    if (!this.get("unsafe-perm")) {
      getUid(this.get("user"), this.get("group"), cb)
    } else {
      process.nextTick(cb)
    }
  }
docs: Call in the context of a npmconf object