Whenever a new portal is created, it sets the spawnpoint to that.
I was reading ( http://tropicraft.net/p/bug-fixes-b-team-and-more/ ) that this was fixed in 5.1.7 but it isn't. I'm running that version and users keep complaining everyday that they spawn at Tropicraft Portals when they die.

Fixed in #64

Cojo asks: have any of the users tried changing their spawn location since they updated to 5.1.7?

We didn't update. We started a fresh server running with 5.7.1 and it happens since the first portal was created. Worked fine before the first portal.

I can confirm this.. We started a Attack of the B-Team 1.0.12a server two weeks ago with Tropicraft 5.1.7, and there have been no updates.

A player created a tropicraft portal, and now world spawn has been moved to the portal.

I'm also trying to figure out if there's an easier way to fix it than stopping server, downloading/editing level.dat with nbtexplorer, and re-uploading/restarting the server.