Comment 3 for bug 1670506

Thanks. I hope that fix gets backported to 16.04 LTS. Until then, I have documented the work-around that worked for me in the Ubuntu Answers mentioned above:
    https://answers.launchpad.net/ubuntu/+question/526440

I'll also suggest an upstream change that would prevent this kind of problem (a new signing key being introduced by the Tor Project after the Ubuntu package is released) from happening again: have the torbrowser-launcher download any updates to its signing keys before it attempts the signature verification.