This command is a sibling to `reassign!`, in the sense that it also creates a commit with a subcommand tag to guide a rebase event. In this case though, the `drop!` indicates that a target commit is supposed to be dropped during rebase. Similar to `ressign!` handling, this type of pin can only be processed with `--squash-minor-bumps`, and the target commit cannot be another pinned commit. This change is being implemented for rebase v2 only. Bug: https://github.com/brave/brave-browser/issues/56150