Multi-commit diffs are unintuitive

[benjiwolff]

Filing this as a bug because the behavior is very unintuitive, though it might be intentional.

1. In the log view in normal mode "diff this" shows the changes of the commit under the cursor (X) from the previous commit i.e. X~1..X. In visual mode when selecting two commits (X and X~1), it shows the same diff X~1..X. I would expect this to show X~2..X instead i.e. to include changes from both commit.
2. When the cursor is placed on the last line of the selection, "diff this" shows the backward diff X..X~2. To me this is very unintuitive, since selecting from top to bottom is the natural direction (cursor starts at the top) and I never want to view commits backwards.
3. In the "recent commits" view, multi-commit diffs don't work. Instead, only the commit under the cursor is shown.

#1784 fixes the behavior for me. Do you agree that multi-commit diffs should work like this?