Git attributes ignored for root directory

Hello,

I just updated to git v1.7.7 using the Ubuntu Lucid PPA and I found that `git check-attr` is broken now.

I have this attribute in my `$HOME/.gitattributes` file:

     /. show_in_prompt=no

Now, if I go to `$HOME` and run

     git check-attr show_in_prompt -- .

With git v1.7.6 this is the answer I got:

     .: show_in_prompt: no

With the newer v1.7.7 I get this, instead:

     .: show_in_prompt: unspecified

Also, if I use the `--all` option, `check-attr` does not show any attribute at all.

I see in the release notes of 1.7.7-rc1 that `check-attr` has been changed to allow relative paths to be specified. Maybe this error is related to that change.

Best,