phinze/homebrew-cask — pull request #1247 by phinze (2013-10-20 21:54:47+00:00)
Title: require most commands to succeed; cleanup on install failure

- add `run!` method which raises if command does not succeed
- use `run!` when the command we are running must succeed for things to
move forward. this should help produce clearer error messages in
failure scenarios.
- move caveats earlier in the install process so reports can be made
about potential failures
- remove the destination tree on cask install failure, so the cask will
not be considered installed