Merge "[FileBackend] Changed copy script to use batches for concurrency."

diff --cc maintenance/copyFileBackend.php
index 07f6199,8d20533..530b5ca
--- 1/maintenance/copyFileBackend.php
--- 2/maintenance/copyFileBackend.php
+++ b/maintenance/copyFileBackend.php
@@@ -1,7 -1,13 +1,7 @@@
  <?php
  /**
-  * Copy all files in one container of one backend to another.
+  * Copy all files in some containers of one backend to another.
   *
 - * This can also be used to re-shard the files for one backend using the
 - * config of second backend. The second backend should have the same config
 - * as the first, except for it having a different name and different sharding
 - * configuration. The backend should be made read-only while this runs.
 - * After this script finishes, the old files in the containers can be deleted.
 - *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or