Fwd: $LOCAL and $REMOTE swapped for rebase mergetool

Fwd: $LOCAL and $REMOTE swapped for rebase mergetool

[Noam Raphael]

Hi,

When using `git mergetool` with `git merge`, the variables $BASE,
$REMOTE, $LOCAL and $MERGED behave as I would expect.

However, when using `git rebase` instead of `git merge`, $LOCAL and
$REMOTE are swapped - instead of $LOCAL being the local content before
the commit and $REMOTE being the content being rebased, it's the other
way round. This doesn't seem consistent with the git-mergetool man
page.

This causes 3-way diff tools to swap the meaning of what's on the left
pane and what's on the right pane. I had to work around this with the
new 4-way diff tool that I wrote (https://github.com/noamraph/meld,
check it out!) since it assumes the diff between BASE and REMOTE
should be applied to LOCAL, and this doesn't hold.

I think that at least the documentation should be updated. Or perhaps
the behavior should change - this actually seems to me like a bug.

Cheers,
Noam