Re: [PATCH] builtin-commit: avoid using reduce_heads()

> 3. Remove reduce_heads() from git-commit entirely, and record in
>    MERGE_HEAD (or rather now MERGE_HEADS) _all_ _reduced_ heads.
>    _All_ means that HEAD is included in MERGE_HEAD if it is not
>    reduced, _reduced_ means that only non-dependent heads are in
>    MERGE_HEAD.  This for example means that for simple non-octopus
>    merge case MERGE_HEAD/MERGE_HEADS now contain _all_ parents,
>    and not only other side of merge.
> 
>    This solution has the advantage of being clear solution, clarifying
>    semantic of MERGE_HEAD (currently HEAD is used both as target, i.e.
>    where merge is to be recorded, and as one of heads to merge/to
>    consider), and making it possible to separate layers: git-merge
>    is about merging, git-commit doesn't need to know anything about
>    merging.