Login redirect bug

I have an issue where I go to `site.dev/wp-admin` and get redirected to `site.dev/wordpress/wp-admin` which is great... except that it reauth=1 gets appended to the url. Which causes a logout as soon as I try and log in.

We should probably be handleing this at the level that the redirect is happening - but I can't for the life of me work out where this is... 

I noticed Joel was experiencing this issue too - although he had got pretty used to it and always remembered to remove the query args from the url.