Merge branch 'cc/bisect-rev-parsing'

Merge branch 'cc/bisect-rev-parsing'

The logic in "git bisect bad HEAD" etc. to avoid forcing the test
of the common ancestor of bad and good commits was broken.

* cc/bisect-rev-parsing:
  bisect: add test to check that revs are properly parsed
  bisect: parse revs before passing them to check_expected_revs()