[Bug] `tig blame --reverse` get the wrong revision of file

When I use `tig blame --reverse` to [find which commit deleted a line?](https://superuser.com/questions/541681/git-how-do-i-find-which-commit-deleted-a-line),  I found that tig gets the wrong file revision. e.g.

`git blame --reverse START_SHA..HEAD file.ext` can get file.ext @ START_SHA, while
`tig blame --reverse START_SHA..HEAD file.ext` can get file.ext @ HEAD



