Hi i am having the same problem.
I downloaded 0.17.0 build 42971 Linux 64 alpha, and now it says that there are no updates.
So do i also need to download the game in full for every new update?

This is the first time i am getting hit by a bug on a experimental release. I have run on experimental sense version 0.11. So it is only to wait for a new release until i can continue to play i guess.