Re: Merge-base alias for git vc-diff

[Juri Linkov]

>> This is another problem, then we need to add the prefix MERGE-BASE
>> to all branches listed in the completions: MERGE-BASE:master,
>> MERGE-BASE:branch-a, MERGE-BASE:branch-b, ...  Too bad.
>
> Maybe we should allow the "old revision" to be of the form "<REV>..."
> and/or the "new revision" to be of the form "...<REV>".

This is the most natural representation, but the only problem is its
discoverability - the users have to learn this syntax.  OTOH, after
typing TAB TAB we can show the virtual revision name MERGE-BASE
in the list of completions, but its drawback is that after selecting
MERGE-BASE we have to show another minibuffer asking for the branch name
where to look for the common ancestor.  Or we could support both ways.