Hi Pablo,
Thanks for bringing this to our attention, it seems Jochen Sprickerhof has changed our key installation in Jade, which is fine, but I wasn't aware he had done that, otherwise I would have changed all of them. I'll look into consolidating our key setup method, but the error with the setup of the key in the Indigo instructions is likely just a temporary problem with GitHub. I am able to fetch and install the key myself, can you try again with the Indigo style key fetch? If nothing else to make sure it is not a systemic issue with that approach.
Thanks,