Don't recheck reviews with a -2 on them

Really, if someone's put a -2 on a review, then what's needed is
discussion between humans, not bot chatter.
Better CI-comment finding

If someone's posted a real comment on a review after a Jenkins failure
(e.g. actual review comments, not bot spew), then the CI comment will
not be in the last 2 comments any more. Now we go look at all the
comments for the newest patch set (or as best we can determine it) to
find the CI and ER comments.
Add option to drop to debugger for specific review

Sometimes the logging just isn't enough.