title: Why does this Travis deploy to Heroku fail?
body: <p>I use Travis CI to build a Ruby app. The app is deployed to Heroku after a successful build. After upgrading from Cedar to Cedar-14 and changing Ruby version to 2.1.4 (as this was required for the stack upgrade) the deploy step fails when Heroku precompiles the project. I have tried various deploy strategies but without success. The logs don’t specify the invalid url which makes it hard to track the troubleshoot this issue. From the deploy log:</p>
  
  <p>Running: rake assets:precompile
  rake aborted!</p>
  
  <p>ArgumentError: invalid url</p>
  
  <p>/tmp/build_4345603424563456/vendor/bundle/ruby/2.1.0/gems/redis-3.0.7/lib/redis/client.rb:364:in `_parse_options’</p>
  
  <p>When I push the app straight to Github, the deploy is successful and the stack upgrades to Cedar-14. </p>
  
  <p>So, why does the Heroku deploy step suddenly fail when using Travis CI?</p>