git diff --summary only seems to work when combined with --stat

Hi,

It seems like the --summary option only works in combination --stat.

It doesn't seem to work if I use it by itself, nor in combination with --name-status or --num-stat. And depending on the order, it either does nothing, or causes a usage note.

Is this intentional? If so, could it be reconsidered? At the very least in combination with --name-status and by itself, I can kind of understand it not working with --numstat

Ive tested with two gits, and it seems to be the same in both:

git version 1.7.2.1 and git version 1.7.3.2.168.gd6b63

Cheers, yves

$ git diff --summary --stat HEAD^
 somefile |   14 ++++++++++++--
 1 files changed, 12 insertions(+), 2 deletions(-)
$ git diff --summary HEAD^
$ git diff --summary --numstat HEAD^
12      2       somefile
$ git diff --summary --name-status HEAD^
M       somefile
$ git diff --name-status --sumary HEAD^
usage: git diff <options> <rev>{0,2} -- <path>*
$ git diff --numstat --sumary HEAD^
usage: git diff <options> <rev>{0,2} -- <path>*