Redmine backlogsの設定が変更できないのはDBがおかしかった

久しぶりにbacklogsの設定を変更しようとしたがいくら変更しても一向に変更されない状態になった。保存時のログは以下のような感じで特段エラーっぽくみえない。

Started POST "/settings/plugin/redmine_backlogs" for 192.168.0.12 at 2013-11-21 17:09:43 +0900
Processing by SettingsController#plugin as HTML
 Parameters: {"utf8"=>"\u2713", "authenticity_token"=>"lozyrps/WYBAkxbZSTJ1NR5IoakJ/eJN2Tl10Qi5s9w=", "settings"=>{"story_trackers"=>["2"], "task_tracker"=>"3", "points_burn_direction"=>"down", "card_spec"=>"APLI 01
293", "taskboard_card_order"=>"story_follows_tasks", "wiki_template"=>"", "burndown_print_width"=>"", "burndown_print_height"=>"", "show_burndown_in_sidebar"=>"enabled", "story_points"=>"1,2,3,5,8,13", "autorefr
esh_wait"=>"1000"}, "commit"=>"\u9069\u7528", "id"=>"redmine_backlogs"}
Redirected to https://192.168.0.20/settings/plugin/redmine_backlogs
Completed 302 Found in 16ms (ActiveRecord: 1.5ms)

DBを覗いたらbacklogsの行が2行存在した。

mysql> select * from settings where name='plugin_redmine_backlogs';
+----+-------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+---------------------+
| id | name                    | value                                                                                                                                                                                                                                      | updated_on          |
+----+-------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+---------------------+
|  1 | plugin_redmine_backlogs | ---
:story_trackers:
- 2
:task_tracker: 3
:card_spec:
:taskboard_card_order: story_follows_tasks
:story_points: '1,2,3,5,8'
:show_burndown_in_sidebar: enabled
:points_burn_direction: down
:wiki_template: ''
                          | 2012-08-29 21:37:59 |
|  2 | plugin_redmine_backlogs | ---
:story_trackers:
- 2
:task_tracker: 4
:card_spec:
:taskboard_card_order: story_follows_tasks
:story_points: '1,2,3,5,8'
:show_burndown_in_sidebar: enabled
:points_burn_direction: down
:wiki_template: ''
:auto_assign_task: enabled
| 2012-08-29 00:00:00 |
+----+-------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+---------------------+
2 rows in set (0.00 sec)

このうち、設定画面に反映されていない方を delete してやったら回復した。

mysql> delete from settings where id = 2;

そもそも何で2行存在していたのかは不明。ログを詳細にしたらもっとサクッと気づいたかもしれない。
バージョンはRedmineが2.0.3, backlogsが v0.9.26。古い。