ivy-completing-read, read-file-name-internal. Wrong completion if initial filename is given?

This works like it should:

``` elisp
(ivy-completing-read "test: " 'read-file-name-internal 'file-exists-p t "~/.emacs.d/")
```

this doesn't(it starts prompt from current directory):

``` elisp
(ivy-completing-read "test: " 'read-file-name-internal 'file-exists-p t "~/.emacs.d/init.el")
```

standard `completing-read` works correctly in both cases.
