opscode-cookbooks/homebrew — pull request #56 by jeroenj (2014-09-24 11:52:35+00:00)
Title: Don't upgrade casks when an older version already is installed

`brew cask list ` will return with a non-zero exit code if the installed cask version is not the latest. This breaks idempotence of this resource when a newer version of a given cask available.
`brew cask list` will include older versions of casks so grepping that list will give us an actual result if it's installed or not.