Re: Merge-base alias for git vc-diff

[Dmitry Gutov]

On 27.12.2018 0:32, Juri Linkov wrote:

> Since "git diff A...B" is equivalent to "git diff $(git-merge-base A B) B",
> doing the same means adding a new alias "MERGE-BASE" to the completions of
> `C-u C-x v D' (vc-root-diff) to complement the existing alias "HEAD".

Do we have aliases like that in VC? HEAD is simply a ref that Git 
recognizes, but MERGE-BASE is not (*). Not sure how to handle it best.

Maybe you'll want to both extend the 'diff' backend command and add a 
new boolean argument to the end.

And also add a new command that would use it, similar to 
vc-root-version-diff (or a new meaning to some value of the prefix 
argument).

(*) Also: merge-base with what? master is not always the base.