Fixing rebase rather than avoiding it

[Teemu Likonen]

* 2010-03-05 13:08 (+0900), Stephen J. Turnbull wrote:

> Eg, in git, running bisect only on the left-hand ancestry in general
> might best be done by creating a temporary branch with git
> filter-branch. (This operation is generic and easily automated.)

I'd just test if the current commit is in the first-parent line. So the
first lines of "git bisect run" script:

    #!/bin/sh
    git rev-list --first-parent master | \
        fgrep --quiet $(git rev-list -1 HEAD) || exit 125

Now we bisect only the first-parent line.