Posting a link to the last post within that topic by using /t/topic-slug/123/last used to work great, but it seems to be broken after a recent update.
Entering the url in the address bar still works and will take you to the last post, but clicking on the link will just redirect you to the first post.
example on try.discourse:
http://try.discourse.org/t/internal-link-test/332/
go to the last post on this topic:
https://meta.discourse.org/t/link-to-last-post-in-topic-no-longer-works-after-recent-updates/32415/last