The `reword` command of an interactive rebase used to call the
commit-msg hooks, but that regressed when we switched to the
rebase--helper backed by the sequencer.
Noticed by Sebastian Schuberth.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>