From: Junio C Hamano <gitster@pobox.com>
Date: Wed, 04 Apr 2012 20:26:46 GMT
Subject: Re: rebase -p loses amended changes
Message-ID: <7viphf8cqh.fsf@alter.siamese.dyndns.org>
In-Reply-To: <7vpqbna0cd.fsf@alter.siamese.dyndns.org>

Junio C Hamano <gitster@pobox.com> writes:

> Johannes Sixt <j.sixt@viscovery.net> writes:
>
>> IMO, it is a sub-optimal implementation of rebase -p that it attempts to
>> redo the merge. A better strategy is to just replay the changes between
>> the first parent and the merge commit, and then generate a new merge commit:
>>
>>    git diff-tree -p M^ M | git apply --index &&
>>    git rev-parse M^2 > .git/MERGE_HEAD &&
>>    git commit -c M
>>
>> This would side-step all the issues discussed here, no?
>
> Or cherry-pick the change made by the merge to its first parent, i.e.
>
> 	git cherry-pick -m 1 M

Err, that was a confusing unfinished message.  I meant the step to replace
the part that uses pipe to "git apply", more like

        git rev-parse M^2 >.git/MERGE_HEAD &&
	git cherry-pick --no-commit -m 1 M &&
        git commit -c M

The primary difference is that, because "apply -3" is not implemented yet,
this will help when the base has drifted too much from the corresponding
blob recorded in M^.