Re: [PATCH] git-commit --amend: respect grafted parents.

> This allows a poor-mans-filter-branch of the top-most commit.
> 
> Specifically, I had this history:
> 
>    --o--o--A'    <-- amended version of A
>          \
>           A
>            \
>     --o--B--M
> 
> I now wanted to "amend" M to pull in A' instead of A as its second 
> parent. For various reasons I didn't want to redo the merge M again, in 
> particular, it already contained the changes that were amended into A'. 
> So I figured I would just install a graft that lists B and A' as parents 
> of M and then do a simple git commit --amend. Alas, git commit looks at 
> the real parents instead of the grafted ones, so the amended M' would 
> still have A as its second parent. Here is the fix that picks the 
> grafted parents instead.