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I tested the latest version, and yes, it doesn't work. But, I was checking the README and it says that the contents of this repo is distributed through releases in Arduino IDE. (Tools > Board > Boards Manager > Intel Curie Boards by Intel). I think that it is the stable version.
The README also says that If you wish to use the latest untested changes, follow some instructions. And the last sentence says: "Future upgrades may fail since the internal contents were modified by hand. In order to recover, shut down the IDE, delete the entire Arduino15 directory, then restart the IDE." So, yes it can fail because it is untested.
Have a nice day.