### Please describe the problem.

I understand that `git annex unannex` is essentially there for undoing an accidental `git annex add`. Unfortunately it doesn't do that.

If I have uncommitted changes, which is the case after a `git annex add`, it tells me:

    git-annex: Cannot proceed with uncommitted changes staged in the index. Recommend you: git commit
    CallStack (from HasCallStack):
      error, called at ./Command/Unannex.hs:48:19 in main:Command.Unannex

But I would expect it to `git reset` the file and then replace the symlink by the actual file content.

### What steps will reproduce the problem?

    > git init
    Initialized empty Git repository in /somewhere/.git
    > git annex init
    init  ok
    (recording state in git...)
    > touch foo
    > git annex add foo
    add foo ok
    (recording state in git...)
    > git annex unannex foo
    git-annex: Cannot proceed with uncommitted changes staged in the index. Recommend you: git commit
    CallStack (from HasCallStack):
      error, called at ./Command/Unannex.hs:48:19 in main:Command.Unannex

### What version of git-annex are you using? On what operating system?

git-annex version: 6.20160527-gf21a425

Installed from the Arch Linux repository.

### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)

Sure, I'm using it for photos, music and videos
