I have touched the Aclugs / Deep Island server code for the first time in... forever to fix a long-standing open issue: proper implementation of plNetMsgTestAndSet. Thanks a lot to Hoikas for showing me how this is implemented in dirtsand, which was tremendously useful!
I have no idea what will be the consequences of this in-game, so please keep your eyes open and let me know here if you notice anything change. This might either fix existing bugs, or introduce new bugs, or both, or neither; it should only have any effect when there are multiple players in an age. I guess we will see.