My organization uses a redirect on the landing page after someone makes a contribution so they can fill our a survey for us. This redirect is triggering when we are trying to edit the "Thank you and receipting" information on the back-end of the donation page after upgrading to 4.6 (it didn't previously). This is also happening on the demo site (see the "Member Signup and Renewal" page).
This seems like a bug to me, but I wasn't sure, so I thought I would ask about it here before reporting it. The pages can still be edited if you push the stop button on your browser at the exact right moment before the redirect takes hold, it is just annoying to work around.