buildbot/buildbot — pull request #594 by djmitche (2012-12-20 01:44:01+00:00)
Title: handle errors showing tracebacks better

As a result of some conversation in IRC. It looks like Twisted has trouble formatting unmarshalled tracebacks. This just fixes the handling of that: write err.txt first; continue to complete the step even after a failure; and use log.err with a string argument so twistd.log does not claim "Unhandled error".