Kudos on the new redirect for migrated, deleted questions! One small problem though: it appears to fall apart when the question is deleted on the destination site as well...

Steps to reproduce

1. Find a question that has been migrated, deleted, and then subsequently deleted on the destination site. Here is one example...
2. Log out on both sites (or use an account with <10K rep points)
3. Attempt to navigate to the URL of a question identified in #1
4. Note that your browser informs you of a problem redirecting (or a "redirect loop", or just hangs)
5. (Optional) View the HTTP headers to note that the original URL redirects to the destination URL, which promptly redirects back to the original URL (and the cycle continues)...

There appears to be some subtlety between "migrated from" and "migrated to" that the new code isn't picking up on...