In commit b7bb760d5ed4881422673d32f869d140221d3564 (Fix revision
log diff setup, avoid unnecessary diff generation) an optimization was
made to avoid unnecessary diff generation. This was partly fixed in
99516e35d096f41e7133cacde8fbed8ee9a3ecd0 (Fix embarrassing "git log
--follow" bug). The '--diff-filter' option also needs the diff machinery
in action.
Signed-off-by: Arjen Laarhoven <arjen@yaph.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>