client: add http tracker destroy function

Author: feross

lib/http-tracker.js

@@ -85,13 +85,19 @@ HTTPTracker.prototype.setInterval = function (intervalMs) {
   }
 }
 
+HTTPTracker.prototype.destroy = function () {
+  var self = this
+  self.destroyed = true
+}
+
 HTTPTracker.prototype._request = function (requestUrl, opts, cb) {
   var self = this
 
   var u = requestUrl + (requestUrl.indexOf('?') === -1 ? '?' : '&') +
     common.querystringStringify(opts)
 
   get.concat(u, function (err, data, res) {
+    if (self.destroyed) return
     if (err) return self.client.emit('warning', err)
     if (res.statusCode !== 200) {
       return self.client.emit('warning', new Error('Non-200 response code ' +