Re: git diff: support "-U" and "--unified" options properly

Linus Torvalds [off-list ref] writes:

[ Maybe this can still hit 1.3.3? ]

Ah, we did not pass the diffopt to the function builtin_diff() in
1.3.X series, so not really.  We could forward port but I do not
know if it is worth the effort of backporting while stripping
the updates of the whole chain of diff generation from the post
1.3.0 "master" work.  I have to think a bit.