git_annex_add_error_with_Andrew_File_System.mdwn

### Please describe the problem.
I have a git annex clone on Andrew File System. I obtain an error when I try
to add a file to the annex:

git-annex: test: createLink: unsupported operation (Invalid cross-device link)

### What steps will reproduce the problem?
Create a test file with touch and add it with git annex add.

### What version of git-annex are you using? On what operating system?
git-annex 4.20130723 on Debian sid.

### Please provide any additional information below.

[[!format sh """
gio@crack:~/nobackup/archive$ touch test
gio@crack:~/nobackup/archive$ git annex add test
add test 
git-annex: test: createLink: unsupported operation (Invalid cross-device link)
failed
git-annex: add: 1 failed
gio@crack:~/nobackup/archive$ logout
"""]]

It seems to me that AFS doesn't support hard links between different
directories.

> [[done]] per comments --[[Joey]]