Fixes bugs introduced into database iterator from way text archive iterator was modified, a=chris

diff --git a/lib/archive_bundle_iterators/database_bundle_iterator.php b/lib/archive_bundle_iterators/database_bundle_iterator.php
index df92e0250..fff1ec533 100644
--- a/lib/archive_bundle_iterators/database_bundle_iterator.php
+++ b/lib/archive_bundle_iterators/database_bundle_iterator.php
@@ -138,6 +138,9 @@ class DatabaseBundleIterator extends ArchiveBundleIterator
             $this->encoding = "UTF-8";
         }

+        if(!file_exists($result_dir)) {
+            mkdir($result_dir);
+        }

         if(file_exists("{$this->result_dir}/iterate_status.txt")) {
             $this->restoreCheckpoint();