message: Fail fast when we caannot parse the user given ref.
diff: @@ -77,6 +77,11 @@ fi
  #get the hash from nice names like tags/v2.0.0
  remoteref=$(git rev-list -n 1 "${ref}")
  +ret=$?
  +if [ $ret -gt 0 ]; then
  + echo "could not parse ref ${ref} exiting"
  + exit 1
  +fi
  unixtime=$(git show -s --format=%at ${remoteref})
  