Terran Addons don't build reliably for a second player

We've noticed that the terran building addons are not built when playing as the second player. This can be easily seen by running the intermediate_bot with 2 instances of the TerranMultiplayerBot from the examples. You can see that the first bot will always build the addons, and end up with a massive supply advantage because of it, when both bots should be identical.