Re: [PATCH v3] Accept tags in HEAD or MERGE_HEAD

>>  static unsigned char head_sha1[20];
>> +static struct commit *head_commit;
>
> I was not happy with the file-scope global head_sha1[] already, and this
> makes me even less happy. Was it too much trouble to keep them local to
> cmd_commit() and pass them around as arguments where necessary?  If you
> pass around head_commit, is_null_sha1(head_sha1) can be replaced with a
> check !head_commit so we may even be able to lose the head_sha1[] global.
>
> And actually removing head_sha1[] is a necessary step from the correctness
> point of view. The repository may have given an object name for a tag in
> head_sha1[] and lookup_expect_commit() may have peeled it to a commit.
> The code may want to add the "HEAD" as one of the parents of a new commit,
> and head_sha1[] is no longer the place to pick that information up after
> your fix. The code needs to look at head_commit->object.sha1[] instead.
> Losing the use of head_sha1[] variable and forcing the code to go to
> head_commit->object.sha1[] reduces the risk of such confusion.