Force re-load an object when purging so we don't try to access things that no longer exist in Fedora.

includes/tuque_wrapper.inc

@@ -298,7 +298,14 @@ class IslandoraFedoraApiM extends FedoraApiM {
 
         default:
           $ret = parent::purgeDatastream($pid, $dsid, $params);
-          islandora_invoke_datastream_hooks(ISLANDORA_DATASTREAM_PURGED_HOOK, $object->models, $dsid, $object, $dsid);
+          // We need to remove this object from the cache and reload it as
+          // Tuque may not have an updated copy. That is the datastream could
+          // still be present within the object even though it's purged out of
+          // Fedora.
+          $tuque = islandora_get_tuque_connection();
+          $tuque->cache->delete($pid);
+          $non_cached_object = islandora_object_load($pid);
+          islandora_invoke_datastream_hooks(ISLANDORA_DATASTREAM_PURGED_HOOK, $non_cached_object->models, $dsid, $non_cached_object, $dsid);
           return $ret;
       }
     }