GitHub auth: use UTC epoch seconds instead of milliseconds

lib/github-auth.js

@@ -140,12 +140,16 @@ function rmReqRemaining(token) {
   reqReset.delete(token);
 }
 
+function utcEpochSeconds() {
+  return ((Date.now() / 1000) >>> 0);
+}
+
 // Retrieve a user token if there is one for which we believe there are requests
 // remaining. Return undefined if we could not find one.
 function getReqRemainingToken() {
   // Go through the user tokens.
   // Keep the first one which is usable or has reset.
-  var now = +new Date();
+  var now = utcEpochSeconds();
   for (var token of reqReset.keys()) {
     var reqs = reqRemaining.get(token);
     var reset = reqReset.get(token);
@@ -212,9 +216,10 @@ function githubRequest(request, url, query, cb) {
         rmGithubToken(githubToken);
       } else {
         var remaining = +res.headers['x-ratelimit-remaining'];
+        // reset is in UTC epoch seconds.
         var reset = +res.headers['x-ratelimit-reset'];
         console.log('GitHub auth: token', githubToken, 'rate limit', remaining,
-          'reset', reset, 'now', +new Date());
+          'reset', reset, 'now', utcEpochSeconds());
         setReqRemaining(githubToken, remaining, reset);
       }
     }