I've just tested the script and I'm going to install the patch
to all active branches.

contrib/ChangeLog:

	* git-backport.py: The script did 'git co HEAD~' when
	there was no modified ChangeLog file in a successful
	git cherry pick.
	Run cherry-pick --continue without editor.

(cherry picked from commit 24663f1f6d709daf8913484914ed01af9f7a480a)