`git rebase -i` already know how to interpret single-letter command
names. Teach it to generate the todo list with these same abbreviated
names.
Based-on-patch-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Liam Beguin <liambeguin@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>