Not to argue in either direction, but I think you should be able to "fix" the bisect problem with a script like this:

  #!/bin/bash
  bad=$(git rev-parse "$1")
  good=$(git rev-parse "${@:2}")
  
  git bisect start "$bad" $good
  
  filter=$(echo "$good" | sed 's/^/^/' | cat <(echo "$bad") - | xargs)
  comm -13 \
      <(git rev-list --first-parent $filter | sort) \
      <(git rev-list                $filter | sort) \
      | xargs git bisect skip

I haven't tested it all too thoroughly, but from what `git bisect view` tells me, this seems to work like a `git bisect --first-parent`. I'm wondering why there is no such option...

For anyone unfamiliar with git extension scripts: You should be able to put it in an executable (`chmod +x`) file (say `git-bisect-branch`) in your $PATH to make it usable (`git bisect-branch $bad $good...`).