When diff.renames is turned on, the diff-filter will not return renamed
files (or copied ones with diff.renames=copy) and potential non-ASCII
characters would not be caught by this hook.
Use the plumbing command diff-index instead of the porcelain one to not
be affected by diff.rename.
Signed-off-by: Julian Prein <druckdev@protonmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>