Merge remote-tracking branch 'Marc/ticket/12170' into develop

* Marc/ticket/12170:
  [ticket/12170] Test for 12170
  [ticket/12170] Assign schema keys in migration helper with data_depth 1

phpBB/phpbb/db/migration/helper.php

@@ -53,7 +53,7 @@ class helper
 						$steps[] = array(
 							'dbtools.perform_schema_changes', array(array(
 									$change_type	=> array(
-									$value,
+										(!is_int($key)) ? $key : 0	=> $value,
 								),
 							)),
 						);