One of my oldest non-committed Drupal core features is the deceptively-simply named “Add Referrer Banning“. It’s been around since 2005 when 4.6/4.7 was cool 🙂 It’s been re-rolled 5 times, the last to make it compatible with the HEAD that will be 7.x, that was March 3 of this year.
Since then core has changed a lot, and most importantly, the core functionality that I was hooking into to add the referrering banning has been partially removed. So now I’m wiriting an even more complex patch; from 8KB to something around 30KB.
The lesson here? Whatch the queue and re-roll your patches frequently! Now, I need to get back to digging through system.admin.inc 🙂