Problems with git cl

[Marc Hohl]

Hello all,

I have done some work to issue 659. I have drwan the alternate segno 
symbol and
in addition, I'll provide new bar commands for easier use.

But I don't manage to upload it to rietveld.

1) I have a google account
2) I have downloaded git-cl
3) I have a branch called "varsegno" in my local git repository

I did

$ git add ...

the files, then

$ git commit,

then

$ git format-patch origin

and afterwards

$git cl upload <SHA1>

which I obtained from gitk &

I was asked to edit the message for the code review, but then it stops with

No output from ['git', 'diff', '--no-ext-diff', '--full-index', 
'72a4d16977328a91ceb2b83b0a4d09d750129c26', '-M']

I think I just have overlooked the obvious somewhere. Can someone tell 
me what am I doing wrong?

Thanks in advance

Marc