test B = $(git cat-file commit HEAD^ | sed -ne \$p)
'
+test_expect_success 'rebase -i, with <onto> and <upstream> specified as :/quuxery' '
+ test_when_finished "git branch -D torebase" &&
+ git checkout -b torebase branch1 &&
+ upstream=$(git rev-parse ":/J") &&
+ onto=$(git rev-parse ":/A") &&
+ git rebase --onto $onto $upstream &&
+ git reset --hard branch1 &&
+ git rebase --onto ":/A" ":/J" &&
+ git checkout branch1
+'
+
test_done