git rerere forget isn't working?

So I want a way to clear out the whole rerere cache (i.e. every
remembered conflict resolution). So I try this command:

$ git rerere forget .

It completes silently, I look at .git/rr-cache and there are still a
bunch of SHA1 directories in there. So I guess it didn't work. The
only way I can do this is to physically delete the .git/rr-cache
directory. I'd rather not do this, so is there a way to get this
command to work properly? I'm using git 2.1.0 on Windows.