travis upload to github fails on wrong credentials

[tebeka]

See this job for example:

/home/travis/.rvm/gems/ruby-2.4.1/gems/octokit-4.6.2/lib/octokit/response/raise_error.rb:16:in `on_complete': GET https://api.github.com/user: 401 - Bad credentials // See: https://developer.github.com/v3 (Octokit::Unauthorized)