Update: The ban is postponed, we are working on a solution.

Let's hope the rest of the trackers will follow.

For those interested the issues has been identified by the admins on HDBits. This info has been posted in most of the forums which are currently banning rTorrent 0.9.6. The HDChina admin has acknowledge the post "Got it. We'll check on that." so fingers crossed their ban should be lifted soon.

HDBits admins quote:

For those interested (with the rtorrent 0.9.6 ban on some trackers), we had debugged and solved the problem shortly after opening this thread. The problem was duplicate peer_ids across multiple users. Whether this is the consequence of something rtorrent did with a prng function, intended or not, I don't know, but the solution was extremely simple.
I won't go into detail, but our tracker pre-supposed that peer_id was unique and tried to fetch the peer data from the database using only the peer_id. All we did was add another condition to the SQL statement: AND userid = $userid. The userid should already be present because it can be derived from the passkey.

There are some additional post with more detail but in summary rTorrent is fully compliant with the bittorrent specification (peer_id can be any 20 random bytes) and its the tracker software that is the issue



Update
CHD have been given the exact details they need to rectify the issue with their tracker by Notthegrinch with his original post from HDB. So if they can't fix it now and lift the ban then it wouldn't reflect well on their ability to run a tracker.

just change the SQL query to add "AND userid = $userid LIMIT 1" where $userid is derived from the passkey