* in a post-step, build status can either be "null" or "SUCCESS" to indicate success.
* before we do an scm checkout for stages that post to the comment, set a default "we failed ¯\_(ツ)_/¯" comment.
Signed-off-by: Michael Stack <stack@apache.org>
Signed-off-by: Mike Drob <mdrob@apache.org>