Re: [PATCH] test_must_be_empty: make sure the file exists, not just empty

> The helper function test_must_be_empty is meant to make sure the
> given file is empty, but its implementation is:
>
>         if test -s "$1"
>         then
>                 ... not empty, we detected a failure ...
>         fi
>
> Surely, the file having non-zero size is a sign that the condition
> "the file must be empty" is violated, but it misses the case where
> the file does not even exist.  It is an accident waiting to happen
> with a buggy test like this:
>
>         git frotz 2>error-message &&
>         test_must_be_empty errro-message
>
> that won't get caught until you deliberately break 'git frotz' and
> notice why the test does not fail.
>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>