How? I tried recreating the scenario from the article (the section "First rebase –onto") and ran the first rebase with "--update-refs":

  $ git checkout feature-1
  $ git rebase --update-refs main
  Successfully rebased and updated refs/heads/feature-1.
  Updated the following refs with --update-refs:
   refs/heads/feature-2-base

But all it did was update feature-2-base. It still left feature-2 pointing to the old commits. So I guess it automates "git branch -f feature-2-base feature-1" (step 3), but it doesn't seem to automate "git rebase --onto feature-1 feature-2-base feature-2" (step 2).

Presumably I'm doing something wrong?

Yeah, you need to rebase the tip of the feature branch stack. git will then update all the refs that point to ancestor commits that are moved. So in this case

    $ git rebase --update-refs main feature-2

Thanks! Yup, that does the trick.

First, you don't need the extra "marker" commit. This flag obviates the entire workflow.

Second, you run it on the outermost branch: feature 2. It updates all refs in the chain.