Repro:
- Create User:Liangent/test2.js
- Move it to User:Liangent/test2js
- Try to edit User:Liangent/test2js , a MWException page is thrown (with normal skin).
- Move it further to User:Liangent/test2js.css
- Try to edit User:Liangent/test2js.css , another MWException page is shown (without skin and i18n)
- Move it back to User:Liangent/test2.js
- Try to edit User:Liangent/test2.js , the first type of MWException page is shown now