Stop PubsubHubbub from subscribing if it is not enabled.

CHANGELOG.txt

@@ -4,6 +4,7 @@
 Feeds 6.x 1.0 xxxxx xx, 2010-xx-xx
 ----------------------------------
 
+- alex_b: Stop PubSubHubbub from subscribing if it is not enabled.
 - #711664 neclimdul: guarantee compatibility with CTools 1.4  by declaring that
   Feeds uses hooks to define plugins via hook_ctools_plugin_plugins().
 - #718460 jerdavis: In FeedsNodeProcessor, clear items only for the current

plugins/FeedsHTTPFetcher.inc

@@ -138,14 +138,18 @@ class FeedsHTTPFetcher extends FeedsFetcher {
    * Override sourceSave() - subscribe to hub.
    */
   public function sourceSave(FeedsSource $source) {
-    $this->subscribe($source);
+    if ($this->config['use_pubsubhubbub']) {
+      $this->subscribe($source);
+    }
   }
 
   /**
    * Override sourceDelete() - unsubscribe from hub.
    */
   public function sourceDelete(FeedsSource $source) {
-    $this->unsubscribe($source);
+    if ($this->config['use_pubsubhubbub']) {
+      $this->unsubscribe($source);
+    }
   }
 
   /**