[BUG] log --graph corrupts patch

From: Phillip Wood <phillip.wood@talktalk.net>
Date: Mar 19, 2018, 10:21 UTC
Message-ID: <897b7471-037a-78d9-fc11-0624ef657b4d@talktalk.net>

I've just been reviewing some patches with 'git log --graph --patch' and came across what looked like a bug:

| @@ -272,6 +272,9 @@ do
|       --keep-empty)
|               keep_empty=yes
|               ;;
|       --allow-empty-message)
| +     --no-keep-empty)
| +             keep_empty=
| +             ;;
|               allow_empty_message=--allow-empty-message
|               ;;

However when I looked at the file it was fine, "--allow-empty-message)" was actually below the insertions. 'git log --patch' gives the correct patch:

@@ -272,6 +272,9 @@ do
        --keep-empty)
                keep_empty=yes
                ;;
+       --no-keep-empty)
+               keep_empty=
+               ;;
        --allow-empty-message)
                allow_empty_message=--allow-empty-message
                ;;

for some reason adding --graph causes the patch to get corrupted. I've
tried all combinations of --[no-]-indent-heuristic and
--diff-algorithm={patience|minimal|histogram|myers} and they all give
the same result. I've no idea what is going on, it happens with 2.16.2
and recent next and master. I've pushed the commit to github so anyone
who is interested can get it with

git fetch https://github.com/phillipwood/git.git log-graph-breaks-patch

Best Wishes

Phillip