-----> Ruby app detected ! ! Command: 'set -o pipefail; curl --fail --retry 3 --retry-delay 1 --connect-timeout 3 --max-time 30 https://s3-external-1.amazonaws.com/heroku-buildpack-ruby/bu... -s -o - | tar zxf - ' failed unexpectedly: ! ! gzip: stdin: unexpected end of file ! tar: Child returned status 1 ! tar: Error is not recoverable: exiting now

I opened an issue request with Deis a while back for the same problem and they reported it being an upstream issue with slugbuilder.

Edit: Heh, apparently we already talked about this https://github.com/deis/deis/issues/1016