Error callback not firing when hitting rate limit #348

I'm using github-api in Node v4.4.5, and I've found that if I exhaust the 60 request/hour unauthenticated rate limit, then certain functions never call their callback. For example, the following script works normally until I hit the limit, then after that the callback never gets called.

#!/usr/bin/env node
"use strict";
var GitHub = require("github-api");
var gh = new GitHub({});

var username = "divergentdave";
var user = gh.getUser(username);
user.listRepos(function(error, result, request) {
    console.log("hit callback");
    if (error) {
        console.error(error);
        return;
    }
});

pi@raspberrypi ~/github-user-branches $ node check-rate-limit.js 
Limit remaining: 1
Reset date: Mon Jun 13 2016 20:45:09 GMT-0500 (CDT)
pi@raspberrypi ~/github-user-branches $ node example.js 
hit callback
pi@raspberrypi ~/github-user-branches $ node example.js 
pi@raspberrypi ~/github-user-branches $ 

Other methods, such as User.getProfile() properly call the callback with an error object, complete with details of the 403 response from the API server. I haven't arrived at the root cause yet, but it is most likely in Requestable._requestAllPages.

I'd be up for working on a PR for this, but first, testing for this issue should probably be done with fixture data for the HTTP responses, rather than hitting the GitHub servers directly. Do you have any preferences for which mocking library to use? I see that nock is a popular choice.