How to do the "inverse" of `git rebase <some-branch>`?

Question

In the history below, assume that commits B through E are completely independent from commits F through I.

                       br-1            master
  ⋯ ---A---B---C---D---E---F---G---H---I

How do I end up with a history that looks like this:

                       master
  ⋯ ---A---F'--G'--H'--I'
        \
         `-B---C---D---E
                       br-1

?

br-1 and master are meant to be branches. The prime in F' is meant to indicate that commit F' consists of exactly the same changes as those that went into commit F. Similarly for G', H', and I'.

(The desired operation is, effectively, the inverse of doing git rebase br-1 from master, starting from the second history shown above.)

Answer 1

Two options.

1)

git checkout master
git rebase --interactive A

Delete the lines for B through E

2)

git checkout master
git rebase --onto A E

Answer 2

With master checked out:

git rebase --onto A br-1 master