Renaming an article triggers an error, if article exists

[kaputtnik]

On my local copy of widelands-website, there is an error if i try to change the title of an article to an existing title.

How to reproduce:

Make 2 articles with some contents, e.g. "Main Page" and "RedirectPage"
Edit "RedirectPage" and change the title to "Main Page"

See attached file django-Error.txt for errormessage.

If i go to the admin site (http://localhost:8000/admin/wiki/article/) i could see article "Main Page" twice: One with the original content and one with content of "RedirectPage". Possibilities: Delete one of them or change the title of one of them.

Because of every logged in user has the ability to change the title of an article, the error should not be happen. Solutions:

1. hide the title field for normal users: Easy to implement but only admins could change an articletitle
2. if an article with the prefferred titel exists, prevent the title-change ("An article with this title allready exists").

[kaputtnik (franku)]

> If i go to the admin site (http://localhost:8000/admin/wiki/article/) i could see article "Main Page" twice: One with the original content and one with content of "RedirectPage". Possibilities: Delete one of them or change the title of one of them.

Changing the title will return the original page, but the slug gets lost. So history-view do not work anymore and editing an article will trigger another error. The new edits is stored as well.