The sample pre-commit hook script would fail to reject a file name like
"a\nb" because of the way newlines are handled in "$(...)". Adjust the
test to count filtered bytes and require there be 0. Also print all
diagnostics to standard error, not stdout, so they will actually be seen.
Signed-off-by: Jim Meyering <meyering@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>