Team Foundation Build 2013 and Octopus Deploy - How to reject a package when build or unit test fail?

We are using Team Build 2013 to create builds, and Octopus to deploy. The problem is that I can't figure out how to prevent my builds to reach the build server on failure, and finally prevent them from appearing on Octopus when the build or unit test fail. I have change the "Retention Policy" to erase builds when it fails, but Octopus still sees the empty builds. My ultimate goal is to rollback the checkin if the build or unit test fails. But again, I can't find an event called "On Build failure" or something similar. I tried to use the Post-Build Script, but it is not called when a build fails.