Update from 4.0-alpha-2 to 4.0-alpha-3 told me all my extensions were incompatible

My TBB 4.0-alpha-2 (32-bit Linux) popped up a thing saying there was an update ready. I said 'ok get it'. A while later it popped up a window with the title "Software Update" which said that the following extensions were incompatible with this new version, and they would be disabled until they were fixed to be compatible: Torbutton, Tor Launcher, HTTPS Everywhere.

My network here is really crappy -- is it possible there's some "try to reach the thing to check compatibility, if you time out, assume they're not compatible" logic somewhere?

(I'm assuming that the extensions do indeed self-identify as being compatible with all TBB 4.x.)