Re: [RFC] pre-rebase: Refuse to rewrite commits that are reachable from upstream

> Teach the pre-rebase sample hook to refuse rewriting commits on a branch
> that are present in that branch's @{upstream}. This is to prevent users
> from rewriting commits that have already been published.
>
> If the branch has no @{upstream}, or the commits-to-be-rebased are not
> reachable from the upstream (hence assumed to be unpublished), the rebase
> is not refused.
>
> This patch is not an ideal solution to the problem, for at least the
> following reasons:
>
>  - There is no way for the user to override this check, except skipping
>   the pre-rebase hook entirely with --no-verify.
>
>  - The check only works for branches with a configured upstream. If the
>   user's workflow does not rely on upstream branches, or uses some other
>   method of publishing commits, the check will produce false negatives
>   (i.e. allow rebases that should have been refused).
>
>  - The check only applies to rebase. I wanted to add the same check
>   on 'commit --amend', but there's no obvious way to detect --amend
>   from within the pre-commit hook.
>
>  - There may be other rewrite scenarios where we want to do this check,
>   such as 'git reset'. Maybe a pre-rewrite hook should be added?
>
>  - Some (including myself) want this check to be performed by default,
>   since it's mostly targeted at newbies that are less likely to enable
>   the pre-rebase (pre-rewrite) hook, so maybe the check should be added
>   to core git instead.
>
> Discussed-with: Jakub Narebski <jnareb@gmail.com>
> Signed-off-by: Johan Herland <johan@herland.net>
> ---