Fix SearchResponseIterator scroll first page twice (elastic#595)

Author: safecat

src/Elasticsearch/Helper/Iterators/SearchResponseIterator.php

@@ -128,15 +128,13 @@ public function rewind()
      */
     public function next()
     {
-        if ($this->current_key !== 0) {
-            $this->current_scrolled_response = $this->client->scroll(
-                array(
-                    'scroll_id' => $this->scroll_id,
-                    'scroll'    => $this->scroll_ttl
-                )
-            );
-            $this->scroll_id = $this->current_scrolled_response['_scroll_id'];
-        }
+        $this->current_scrolled_response = $this->client->scroll(
+            array(
+                'scroll_id' => $this->scroll_id,
+                'scroll'    => $this->scroll_ttl
+            )
+        );
+        $this->scroll_id = $this->current_scrolled_response['_scroll_id'];
         $this->current_key++;
     }