It seems that on my dev wiki, and at least on test2wiki, there's a thread_root_2 index that is a duplicate...
Be nice if the extension cleans them up
```
+--------+------------+----------------------+--------------+--------------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+--------+------------+----------------------+--------------+--------------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| thread | 0 | PRIMARY | 1 | thread_id | A | 133 | NULL | NULL | | BTREE | | |
| thread | 0 | thread_root | 1 | thread_root | A | 133 | NULL | NULL | | BTREE | | |
| thread | 0 | thread_root_2 | 1 | thread_root | A | 133 | NULL | NULL | | BTREE | | |
| thread | 1 | thread_ancestor | 1 | thread_ancestor | A | 66 | NULL | NULL | | BTREE | | |
| thread | 1 | thread_ancestor | 2 | thread_parent | A | 133 | NULL | NULL | YES | BTREE | | |
| thread | 1 | thread_article_title | 1 | thread_article_namespace | A | 6 | NULL | NULL | | BTREE | | |
| thread | 1 | thread_article_title | 2 | thread_article_title | A | 19 | NULL | NULL | | BTREE | | |
| thread | 1 | thread_article_title | 3 | thread_sortkey | A | 133 | NULL | NULL | | BTREE | | |
| thread | 1 | thread_article | 1 | thread_article_id | A | 19 | NULL | NULL | | BTREE | | |
| thread | 1 | thread_article | 2 | thread_sortkey | A | 133 | NULL | NULL | | BTREE | | |
| thread | 1 | thread_modified | 1 | thread_modified | A | 133 | NULL | NULL | | BTREE | | |
| thread | 1 | thread_created | 1 | thread_created | A | 133 | NULL | NULL | | BTREE | | |
| thread | 1 | thread_summary_page | 1 | thread_summary_page | A | 8 | NULL | NULL | YES | BTREE | | |
| thread | 1 | thread_author_name | 1 | thread_author_id | A | 133 | NULL | NULL | YES | BTREE | | |
| thread | 1 | thread_author_name | 2 | thread_author_name | A | 133 | NULL | NULL | YES | BTREE | | |
| thread | 1 | thread_sortkey | 1 | thread_sortkey | A | 133 | NULL | NULL | | BTREE | | |
| thread | 1 | thread_parent | 1 | thread_parent | A | 133 | NULL | NULL | YES | BTREE | | |
+--------+------------+----------------------+--------------+--------------------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
17 rows in set (0.00 sec)
```
```lang=sql
DROP INDEX thread_root_2 ON thread
```