Redirect to Special page in Plaintext
This bug will appear in RC 2, now that the wiki has a plain-text parser. Rather than fixing it for RC 2, this is being pushed to the next release because of the rather significant changes it will require to Special pages - which aren't a big focus in RC 2.
Essentially, you can already create a redirect page that resolves at a Special page. Normally, redirect pages will display fine under plain-text (RSS feeds and such) because their target pages can be parsed using the plain-text parser. But Special pages are HTML templates and do not go through the parser, and removing the HTML automatically would prove difficult. So a redirect to a Special pages would contain HTML rather than plain-text.
The only way to fix this really is to create plain-text phrases for Special pages.