The PlayerInteractEvent does not appear to be fired correctly when non-operator players right-click blocks or air within the radius of spawn protection (possibly in other places, location not thoroughly tested). This is particularly problematic for plugins like ServerSigns which rely on this event to be fired in all locations on the server.

How I reproduced the issue:
1. Compiled latest Spigot/Craftbukkit builds on 4th August 2015
2. Created a new server by running either jar with this batch file (https://gist.github.com/Exloki/34a87c92cd019431ce7f)
3. Restarted the server with a simple plugin that broadcasts "Interact" into chat whenever the PlayerInteractEvent is fired.
4. Login to the server with an account never previously connected
5. Right-click any block or air within the area spawned - no messages
6. Left-click any block or air in the same location - messages appear