Arbitrary here does not include '', best to catch that one early as it's
almost certainly a mistake (possibly an attempt to pass a POSIX path
through this API)
Signed-off-by: Paul "TBBle" Hampson <Paul.Hampson@Pobox.com>
Since this function is about to get more complicated, and change
behaviour, this establishes tests for the existing implementation.
Signed-off-by: Paul "TBBle" Hampson <Paul.Hampson@Pobox.com>
