Yeah, we had to pull out this change at the last minute due to some bugs it was causing and it didn't get cut from the update notes. This change is still coming, but not this update. Patch notes will be updated soon to remove this line item. Sorry about that, we've wanted to put this change up for a while, but keep running into problems with it!
I just wanted to clarify on this. It was a pretty nasty bug before. It's a bit convoluted so hopefully I can explain it. If you were playing as a medic, got team killed, then revived, it would save the teamkiller as your last killer. Now when you tried reviving people, it looked at your last killer, not your patient's last killer. Thinking it was a teamkill, the xp system wouldn't give you revive xp. This caused some medics to think they were locked-out. This should fix all that.
Also, if a guy is killed 100% team damage, reviving and healing them up to full won't grant any xp. Before you wouldn't get revive xp, but you would get heal xp healing him back up to full. That's more what the patch note was about. They left out what I thought was the more important part of the same bug fix.