look for errors only when job has failed [fixes #63533638]
Merge pull request #98 from mozilla/fix-story/63533638

look for errors only when job has failed [fixes #63533638]

this looks great.  I paused thinking if there were more cases to skip error parsing than just ``passing`` but pending and running won't have logs yet, so it will skip those anyway, and all the others are some kind of error, possibly even restarted ones.  Great catch!!