Merge branch 'cc/bisect'

* cc/bisect:
  git-bisect: allow bisecting with only one bad commit.
  t6030: add a bit more tests to git-bisect
  git-bisect: modernization
  Documentation: bisect: "start" accepts one bad and many good commits
  Bisect: teach "bisect start" to optionally use one bad and many good revs.