Merge branch 'kd/rev-list-bisect-first-parent'

"git rev-list --bisect --first-parent" does not work (yet) and can even cause SEGV; forbid it. "git log --bisect --first-parent" would not be useful until "git bisect --first-parent" materializes, so it is also forbidden for now. * kd/rev-list-bisect-first-parent: rev-list: refuse --first-parent combined with --bisect